Please have him start his own Discussion so that his problem can be addressed. Acting on the assumption that your Mac has a virus will only waste time and compound whatever problems actually exist.
As for the virus issue, see my Mac Malware Guide. It is extremely unlikely that your husband's machine is infected with Mac malware, nor did your Mac become infected through Boot Camp. If you are basing this on scans made with anti-virus software, note that it is not uncommon for a Mac to have Windows malware on it (as an e-mail attachment or copied from a flash drive or something similar), but that does not mean that it is infected. The malware would simply be sitting inertly on the hard drive.
on my computer the problem was that it switched of every time I tried to get something done on it. And when I tried to format it, or install snow leopard it would switch of mid installation,making the software unsusable. I look at this as a virus becaus when I finally managed to format the computer the problem stopped.
My husbands virus, as I call it, Make **** pop up on firefox, no mather what adress you try to access. This might be something else than a virus (adaware or something).
if your friend did not give you the Snow Leopard disk, and kept it himself, then it was most definitely NOT installed in a perfectly legal manner. That's software piracy, regardless of what someone in your local Apple Store told you. The only way that multiple people are allowed to use a single Snow Leopard disk is if they are family members living in the same household.
My friend was living with us at the time, though we are not family. If this is the case, then Apple should educate their storefront employees better. I don´t know if the user agreemens is different from country to country, and that is why he (the employee) gave me permission to do this. I know that the user agreements did at one point brake norwegian law, and they were forced to change it here.