I just bought myself a MacBook Pro and while I'm waiting for it to arrive, I thought I'd just share the various links others have kindly shared with a PC-based ignoramus like me for making the switch to (or back to, in my case!) a Mac:
General Mac basics
For free and useful, take a look at Apple's site. Their support pages are good.
Also, Mac 101 and Switch 101 (which is great if you're moving from PC to Mac)
These might answer many of the questions that crop up in the first few days/ weeks.
Also, Mac Help, Finder> Help> Search usually works well.
For Open University-related questions, try the Mac General website (although this is jam-packed with stuff anyone using a Mac in education would find helpful)
The best news is that Virtual PC is no longer needed. If you need to use a PC, you can install Windows OS onto your Mac- see Mac General for details.
Other recommended sites:
Mac Rumors and Mac OS X Hints - both sites have forums too; you can pick up tips and tricks in those sometimes as well.
Books and Magazines:
Mac OS X Leopard: The Missing Manual, David Pogue
MacUser magazine and website.
Oh, and if you're a student or work in Education... take a look at the deals available via the Apple Education Store. Well worth the saving!