I've had a PC for... oh, 15 years now at least and have never had a virus or any issues with ad-ware either. Haven't ever ran any anti-virus software of any kind either, that crap is just more trouble than it's worth. And few people spend as much time on the 'Net as I do.
The reason Macs haven't ever gotten any major problems with virii is because the market's so small it's not worth the effort to create hostile software. Recently, the recent boom of Apple has created some interest and those programs are on the rise. I wouldn't bet the farm on the relative "safety" of Macs continuing for too terribly much longer as long as Apple's popularity continues to grow. And since Apple hasn't had to deal with virtually the entire hacking community trying to break it like Microsoft has, they haven't had the incentive to plug security holes like MS has.
You need a key that plugs into the parallel port? You mean you have a key? Like one for software? A 'dongle'? For most devices, the adapters work fine, but dongles can be very picky. You'd need to talk to the software developer to see if their dongle will work via an adapter, if a dongle is indeed what you're talking about.
And I wouldn't say that "nothing" has a Parallel anymore. Apple doesn't have them anymore on most of their stuff, but I don't know if I've ever seen an ATX PC motherboard that didn't have an onboard LPT Parallel port. It's still the standard, although slowly dying, for Printers and Scanners.
