I think anybody who'se interested in security should at least read some of the papers from this site. About.com: http://www.av-test.org/
Also have a read of this http://www.virusbtn.com/news/2008/09_02
And another -- although in Dutch the table is clear enough http://security.nl/artikel/22931/1/3..._bovenaan.html
Whilst not Windows 7 per se it's to do with security and could be relevant to your installations.
At least it contains a lot of decent info and hopefully give some peole a bit more understanding into exactly how some of the AV software works and what it's trying to detect.
BTW if you DO get your computer infected in any way you should boot a READ ONLY live CD which can not only format the entire disk but also properly erase it by writing HEX '00's on every cluster / sector as well as refreshing the MBR (Sector 0).
I've sometimes in the past had to recover data from a re-formatted disk -- recover deleted pictures from a photo shoot etc. - and it's not as difficult as you think. There's a lot of decent "Data recovery" stuff out there so apart from a Low level factory reformat which is probably "Militiary grade security" the binary zero's write erase is the next best option as you will have written on every single data area on the disk.
"Traditional" cleansing isn't really good enough since on the case of "re-infection" the virus can use a lot of these "unformatting" methods to read the data and do whatever it was doing before
I wouldn't trust ANY AV software product to be able to cleanse your computer as effectively as doing the "destructive" erase.