.wmv files:

http://www.microsoft.com/windows/windowsmedia/player/wmcomponents.mspx

As for the other media type files -- all available.

Single-button mouse: yes, they have a scroll widget on the modern Mac mice. What is missing is the "right button" and "center button" -- ie, two clickable and three clickable buttons on a mouse.

Little known factoid: the "need" for a three button mouse came from the original SmallTalk-80 programming environment at Xerox PARC when SmallTalk-80 was running on the Alto's and later the "D-machine¹" workstations. SmallTalk-80 was the first (some would argue the second) "pure" object-oriented programming language that assumed the existence of a bit-mapped screen and a mouse. It was then, as it still is today, pretty slick. Sadly, crap like C++ "won" the language "wars." But that's a dyspeptic screed for another day.

The Quasimodo marketing geniuses of the Unix world in the 80's looked at the early/internal Xerox "D-machine" workstations, shrugged their hunchbacked shoulders (such as they could) and said "Duuuuuhhhh... derrrrr.... Guess mice have three buttons! Yes, one, two, three buttons!" and just continued putting out mice with three buttons on workstations. Xerox, meanwhile, decided that users really needed no more than two buttons on a mouse for non-SmallTalk stuff, and that's where Windows went with their mice.

No one ever thought about "so, uh.... why do we need two or three buttons, really?" until Apple came along with the Mac. Certainly, none of the windowed environments on Unix used three mice buttons effectively or uniformly - two was about all they could manage. The Windows environment decided that using two buttons was a way to deal with modality and they kept two of the buttons, with some gameboys and Linux/Unix users of PC's buying three-button mice for their PeeCee's.

In some applications on the Mac (like ports of the SmallTalk-80 environment), you get different functions for a mouse-down by holding the "Fan" or "Apple" key on the keyboard. No big deal.

Networking: Apple has done a very good job at networking on the Mac, right from the start. In Ye Olden Days, the networking protocol for the Mac was AppleTalk, and PC's used Novell, and there was an interoperability issue. Further complicating things was the choice of CPU's - the Mac's used the Motoroloa 68K line of CPU's, and the PC's used the Intel x86 line of CPU's, so in networking there was what is known as an "endian" issue -- that data objects of two or more bytes were "reversed" inside the respective CPU's, which often led to data incompatibility when you tried to open PC files on a Mac without a special application to read or convert PC-based files. But when TCP/IP became the ubiquitous networking protocol in the early 90's (you can thank us at cisco for making this happen), Apple gave it up and switched to IP with their usual flair for hiding all the gruesome details from the user and just "making it happen." The switch to Intel CPU's by Apple in the last couple of years has removed data compatibility issues in file formats, etc. Windows Workgroup file/printer sharing is included on the Mac. Since the mid-90's, Apple sorta grew up and realized that the Macintosh was never going to become the world-dominating system and the path to success lay in dealing with Windows systems better than Windows does.

In general, I think you'd find that Mac OS X will look like a nice, usable point-n-click GUI machine to do all the things you normally do as long as you're not seeking some native implementation of various business, accounting or trading (stocks or commodities) applications. As I've said before, business apps are the Mac's weak spot, and it isn't because of some inability of the Mac to do these things -- it is purely a function of Apple's management and the fact that from about 1995 to 2000, Apple's management treated their developers in a rather shabby manner and Microsoft treated their developers rather well. When Jobs came back to Apple, this was turned around. It used to be (in the 80's and early 90's) that Apple treated their developers the way MS treats them. That five years in the mid-90's sorta set things back in the Apple world and it is taking time to undo that era of stupidity. Mac OS X, if you so choose, can look rather a lot like a *BSD Unix system if you get down to using a shell or doing C programming on OS X. Unix systems either look/feel like "AT&T Unix" (aka "System V" based) or "Berkeley" or "BSD" based, and Apple's OS X sorta feels like a BSD system in the shell or API's. It isn't a BSD system, it is actually based on a microkernel, but that's a technical issue for another day.

DRM: I'll have to write up a long posting/analysis/screed on Microsoft's DRM nonsense in Vista here Real Soon Now. I'm mostly agnostic about operating systems, having used and programmed, oh, about 15 of them. So I'm not one of these dope-smoking, crank-snorting Macintosh fanatics that you might meet (and you will meet them... and you'll sorta wonder what the heck their problem is...). What really puts me off Vista is the bloat and the idea that Microsoft is going to let DRM become a security hole as well as a dictate for users on how the system is structured, right down to the hardware, all to prop up the clowns in Hollywood.

¹ The early Xerox workstations were nicknamed "D-machines" because all the internal project names started with a "D" -- "Dorado," "Dolphin," "Dandelion", "Daybreak" etc. I'd reckon that most people here have never seen one of these critters. If you ever visit computer museums in Boston, Silicon Valley (and I'm told there is one now in Montana(!)), seek out a Xerox workstation. In their day, they were like technology from outer space when they landed on a desktop in the IBM/CDC/Honeywell mainframe-based world of the early 80's. The culture shock was kinda hilarious in hindsight. I remember seeing grizzled IBM mainframe programmers just stand there and look at the Xerox workstations in gob-smacked awe:

"You mean they fit a whole system in there?"

"Yes, John, they did..."

"Uh... where's the disk drive?"

"Its in there, John."

"CPU too? All in that little box? Uh... What about their IO processor?"

"In there." 

"Errr.... (long pause) I don't suppose they have JCL, do they?"

"No, John, they sorta, um, got around the need for JCL."

John: <blink, blink... lookin' like he's just met someone from Alpha Centauri>

Here's what the D-machines looked like:

http://www.digibarn.com/collections/systems/xerox-8010/index.html

And here's what the operator console of an IBM mainframe looked like:

http://www.corestore.org/3278-3.jpg

And here's what the "state of the art" IBM system at the time of the Xerox D-machine introduction looked like:

http://www-03.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP4341.html

So you can get a feel for the culture shock. The big, long cabinet with no features on the left side of the picture is the CPU. No disks, no tapes, no printer or other stuff, just the CPU and memory - up to 8 MB of memory. The tall unit at the rear was the "channel IO processor" and the low units to the right of the tall cabinet were the disks. On the right is the printer and terminal IO processor.

You can see how people of that day were just blown away by the Xerox, mice, bit-mapped displays, etc. It was just too radical for the day. People simply couldn't believe there was a computer in there. The mouse interface was just... unheard of. The Mac was the computer finally brought the idea home that computers could have more than 24 lines of text, 80 columns long. Windows evolved from the IBM worldview of computing, and the Mac from the Xerox view of computing. So going from Windows to the Mac, you will have some adjustment... but once you've done it, you'll look back and wonder "Why did we as a civilization waste so much time getting here?"