Need advice on a good antivirus program for new desktop

I dislike the Norton products, but NIS 2009 seems to get very good user reviews. I have friends with Norton 360 installed, and it works ok but slows things down a bit, and very occasionally deletes something non-malicious that was needed by the OS. (Probably any "all-in-one" type application has the potential to do that, though. It's the risk you run from - like most of us - not wanting to become expert at the guts of the OS and viruses.)
But from what I've read of NIS2009 (and NAV2009) they are smooth, light, and effective.

I agree with first post, I don't like Norton, too many things running in the background, and a few you can't even shut off if you want to, so here is my suggestions....

First, read the PC Security, and Cleaning Windows section of this document, if for any other reason, you know I'm not blowing smoke here..
http://www.tweakguides.com/TGTC.html You need Adobe reader for this.
It's a small doc., (not a huge download)

For anti virus, I use the free stuff, (AVG)and I don't have any problems as of yet. The document above has some names of free, and good anti-virus programs, but in the end it's your choice.

Cleaning programs friendly to Firefox? Here you go..This is a very good cleaning program friendly to.....well everything on my computer,
and I use Firefox, and Google chrome...
http://www.ccleaner.com/

Finally, I also suggest MBam, or Malwarebytes-anti-malware as your all around supplement to anti-virus.
http://www.malwarebytes.org/mbam.php
Good luck, hope these fulfill your needs...