My $0.02 from owning a mac for about 2 years:
Pros:
- Design - looks / feels awesome and luxurious
- Extremely good build quality
- OS X is much easier to use than Win (changing setting, connecting devices, sharing files/internet/whatever is really painless compared to PC's). The OS feels much more stable / thought through than win.
- Portable - my 13" is perfect for travel, and I love the sleep mode - just close the lid and it powers down with minimal power consumption, and when you open the lid you're back to what you were doing in literally 2 seconds.
- Quiet - my MBP is usually impossible to hear if it's on or not unless I play 3d games.
Cons:
- You don't copy/paste with ctrl-c and ctrl-v, but use the Command key instead of ctrl. This was driving me nuts for about 2 months until I adapted

- No home/end and delete buttons, that I also used a lot on PC
- Finder is, to be honest, worthless. I use PathFinder as a replacement now and it works ok.
- Not as much software. Most major PC program exist (office, photoshop, firefox etc) but some software you're used to might not exist. Usually there are reasonable replacements though.
- Price (let's face it, they ARE more expensive than matching pc hardware)
- Gaming - while you can run games like SC2 on mac, they do run much better on windows. It sure is playable, but if you wanna squeeze out more FPS or run on higher settings, you still need bootcamp.
Overall, in my opinion, the pro's are quite big and the con's not that big.. So I'd definitely recommend getting a macbook. There might be a "learning threshold" for a few weeks where you get annoyed with details ("Hey! Why is the menu at the top of the screen and not in the application window!?"), but it'll pass fast and then you'll wonder why you ever used Windows before

Best of luck!
EDIT: Oh, and some additional tips - the 15" perhaps don't look that much smaller than a 17", but they are much more portable. If you're using it for university, don't get the 17" - it's just too bulky. Also, university often means sitting in well-lit rooms with lights in the ceiling and big windows - get the antiglare option or you'll only have a very pricey mirror
