Free anti virus software recommendation?

[Fargo]

Anybody tried Microsoft Security Essentials ?

[MJ]

I'm using Windows XP Media Center Edition SP3, browse using Firefox 2 with the Adblock Plus add-on (among others), use Avast Home Edition, Spybot 1.6.2, SpywareBlaster 4.2, Ad-Aware Free AE, and PeerGuardian 2 and my machine has stayed clean since day one.

[JamesS]

I like Avast, but the requirement to re-register every year means I can't just install it on family member's PCs and forget about it. I put AVG on my sister's computer, which was fine for a while but at some point it decided to install browser toolbars and whatnot and made her computer slow to a crawl when browsing.