God no. I wouldn't touch anything from download.com, I've got so much spyware from them.
Most likely the problem is with the spyware, a lot of the newer stuff will hijack your anti-virus/spyware software and not let it do any scanning at all. Its a big problem if you're trying to do a scan, but the program which does the scanning has been taken over by what its looking for.
I'm working on a bootable CD which will do a scan without loading windows, so that that kind of stuff can't happen. I'm just evaluating what anti-virus software to use right now, so once I do that I'll send you all the details on making it.
EDIT- Well, forget about that. I was planning on basing it off of Bart PE, but decided to look into
UBCD, which is supposed to be an offshoot of it. Turns out UBCD has 10 different anti-spyware programs and 5 different anti-virus tools. I think that that is more than appropriate, and should do just about anyone good. You'll need a cd-burner, and a cd for Windows XP (plus a product key), but most computers come with those now.
EDIT-EDIT- Just make sure to do
this when you build the CD.