I've been using it for a few months now and no complaints. My Norton expired and didn't like the Norton 2006. It seems to hog the system a lot.  Avira's Antivir classic edition is free and looks very professional. It updates on a regular basis, so you don't have to worry about that.

 I would still use your Spybot and Ad-aware.

Here is the link to Avira:

http://www.avira.com/en/download/index.html 

(SP32-20061018-222309.bmp)

SP32-20061018-222309.bmp (68KB - 288 downloads)