As a computer tech, I seem to be running into more and more customers that have a mac rather than a PC. As I have never really done anything reguarding macs, questions arise each time this happens. Such as "Can I scan a mac hard drive for viruses from a pc"? or "How do I do a system restore on a mac?" I would much like to learn what I can about macs, as I can see an opportunity to be able to tell a customer "why yes, I do work on macs." So any info on where I can go to obtain more knowledge reguarding these systems would be fantastic. Not to mention increase my computer work

http://www.macfixit.com/

Well just like for Windows you have to have a virus scanner if you want to do that (I don't know of any online scanners, but they may exist). Here are a couple links for Mac AV:
iAntiVirus
Norton Antivirus

I have not used either of those, so I don't know how good or bad they are. The chances of them having a virus as the cause of their problems is incredibly low though.

System restore doesn't exist on Macs, and it really doesn't need to, the system files aren't messed with by the user unless they are installing an update from Apple. There is TimeMachine in Leopard and Snow Leopard where it backs up to another drive or partition, and you can go in and restore files to a previous date that way, but its not like the Windows System Restore.

You can do a permissions scan and a disk scan from the Disk Utility app, which is typically found in Applications -> Utilities.

Anything manufactured by Symantec and Norton isn't really worth mentioning these days, IMHO.