I get Spysweeper through a site license at work (That covers home PCs as well) and geez, if this is really what a top rated anti-spyware app is, I'd hate to see a crappy one..! It runs ok about 90% of the time, but then it decides to nag me about updating the defs, or running a sweep (Which I see no point in running sweeps if I run one and the system is fine). I can't find ways to turn it off, and the support staff is fairly useless (granted, it's support through work, and not Webroot-- and I have a feeling our "site" version has some options disabled and hidden, although I've dug through the registry)
And if you turn on the "spy communication shield" it locks you out of sites with no way to "Whitelist" sites you DO want, even if they're on the list of "bad" sites-- like ebates.com. (I have to turn it off just to go to ebates)
It's not bad but I'm glad I didn't have to pay for it.
We also get Sophos AV and I haven't tried the latest version, but the last version was CRAP. Took up way too much CPU time, I know there were TONS of issues with the server version. It got so bad that they finally got Sophos to come and do a TWO-DAY training seminar. Which seemed insane that was needed for an anti-virus product. (one of the other departments actually came up with a huge, like 20 page, document along the lines of "ignore the manual, here's how to really make it work right")
Sophos struck me as way overly complicated and not particularly good. (and, strangely enough, there was a massive conflict between installing Sophos AV and Spysweeper; I hope it's fixed now that they're bundled together!
It got so bad with Sophos that a sorta small (but noticeable) group of department got together and demanded that they re-license McAfee enterprise products (which we had but lost in a falling out of some sort). I know lots of people hate McAfee but their enterprise VirusScan has always worked well for me with very little configuration/setup effort involved.
I have been assured that the latest Sophos is much, much better, but who knows.