Glen.
1st would be "Time Machine". Its sweet back up utility, all you need is an external HD
2nd is "Spaces" allows you to run multiple things in multiple windows and easily bounce back and forth.
3rd for you PC guys who just can't find your Windows App to run on a Apple is "Boot Camp"
As I said to Matt, check out:
http://www.apple.com/macosx/guidedtour/ It should really answer most of your questions. For the $129.00 it cost for the upgrade, I think its well worth it for some of the new features you get. You guys have to understand I spend 8-10 hours a day on a Mac running Graphics programs, and anything that will speed up the performance of my box is worth its weight it gold. Not that the Macs I'm running are slow, to the contrary, my newest box has 16 Gigs of Ram and 3TB internal storage. Its a speed demon, but every little things helps.