Dear Hapless Dar:
I've never had a problem with a virus or a trojan on my home computer, which is a Mac. On my pc at work, I've had viruses, trojans, and spyware.. but the computer tech came in and fixed it and now that I use Firefox, nothing else has happened.
When I upgraded my Mac from OS 9.1 to OSX.3 Panther, I had all kinds of problems with settings conflicts between the supposedly backwards compatible OS9 Classic and the new OSX, and I had to completely reinstall the OS twice. I also had to upgrade all my programs and make sure that the computer would never use any of the modem or internet settings from OS9, which meant deleting all those files after translating and backing up every dadgum file I wanted to keep, thousands.
I use two pin drives for backup, one for the pc at work and the other for my Mac at home.. but they're both compatible with each computer. The pin drive is about the size of a small gum package and inserts easily in a USB slot, and backup is just drag n drop on the Mac, all on the surface.. though it's a bit more complex and time consuming on the pc.
Now everything on both computers works great!
Sue