Gotta strongly second what Mike is saying.

If all you do is web browsing, maybe some email that isn't heavy on video and multimedia enclosures, basic word processing of documents you create, basic spreadsheets that you don't need to share with too many other people, reading/printing Adobe Acrobat documents... Linux can work OK.

If you need to interact with lots of people who use Windows, and they use Office, including PowerPoint, etc, trying to exist with Linux can quickly become a pain in the neck.

If you're not someone who likes digging into various quirky issues in computers and computer software, you might not want to take on Linux.

There are good "distributions" of Linux that have really tried to make installation for the first-time user much easier, and then there are the "distributions for Unix demi-gods" distributions. If you've never used Unix (of any flavor) before, you'd best seek out one of the user-friendly distributions.

Unix without some glossy interfaces is about as friendly as an old friend who greets you by kicking you right square in the groin, slapping you on the back, says "Lemme buy you a beer!" and then makes you pay for it. This is coming from a guy who has used Unix in one form or another since, oh, about 1984, and considers Unix-based OS's "fun."