I just installed Microsofts AntiSpyware (Beta 1) from their web site:
http://www.microsoft.com/athome/securit ... fault.mspx
If is currently free and the installation is easy. The download is about 6MB. It has some type of "real-time" protection also.
Currently the scan on my WinXP machine (which I believe to be clean) hasn't yielded anything strange.
We will begin testing this over the next few weeks in the shop. I'd be interested to know if anyone else has tried it and if so, what's your opinion of it?