I have used housecall for absolutely ages!!!! It may appear unfair that it d/l's virus patern etc to your hard drive, but you'll find it's equal in size to any other good virus scanner.
Housecall is absolutely fantastic with the advice it offers to help you clean your machine up after receiving trojans or viruses.
Grrrr. I don't actually use a virus scanner & never have done, so Housecall suits me just fine.