The Advice I Wish I Got When Making This Decision + A Tip About College
There's no one right answer for you and it's no good to repeat what others have said so I'll just share MY experience because I never got the advice I needed when making this same decision a year ago. (I hadn't found MacRumors yet!!!)
I'm a sophomore chemistry major at Purdue and I came here with a beautiful, new 2.4 Macbook Pro/4GB RAM, blah, blah, blah...
At the foot of my bed in my dorm, sits a new, 46" Samsung LCD right next to a PS3 and stereo. I mention this only so I can now emphasize that my MBP is, without any exaggeration, 10-15 times more of a distraction than any combination of my other toys. On that note... unless you are somehow employed in a field that requires the use of demanding, mac-compatible software... when you purchase a mac, you are primarily purchasing a TOY... it's just a toy that can also function as a high quality tool.
As far as my academic NEEDS go (web browsing, email, word processing, some minor academic sofware)... a $150 windows laptop would have served equally. The entire concept of "buying a mac for school" is nothing more than successful marketing by Apple.
Since no Apple product is going to do squat for your GPA, my advice is to re-evaluate the basis on which you are making this decision and leave education out of it... you're simply buying a machine that will make you happy just the same as deciding to own a nice car instead of a junker... identical functionality, but a very different feeling/grace. So consider...
- Do you want to take it with you anywhere... ever? Get the laptop/desktop thing sorted out first... this is also where you should weigh in how much screen you want to look at... if you have a compatible LCD, I can't imagine buying a desktop, personally... if you don't and you're okay with leaving your mac in one spot indefinitely... then a 24" iMac screen will make any laptop screen look sad and homely.
- Compare each spec thoroughly... example: if you're an absolute sucker for a pretty display... the LED's are noticeably brighter and more true to color and don't exist on the macbooks (yet).
- Will you use it for anything graphically demanding? A macbook can handle a hell of a lot, certainly more than you'd expect from such a tiny thing, but my MBP dances circles around Final Cut and runs Crysis/Bioshock via bootcamp perfectly... obviously, you'd see equal-to and greater performance in an iMac.
- Lastly, this one may not apply to you, but it was a huge issue for me... imagine yourself owning each mac you're considering and then imagine having a roommate that has a different mac... which other macs would make you jealous? I first bought a black macbook to save money (wonderful machine), but five weeks later, I got my hands on my friends macbook pro... I sold the macbook a week later when my MBP arrived. I only lost $100 on the macbook, but thats still lost money. Macbooks, or any other "less expensive" macs are definitely NOT lacking... but if you drool a bit over the pro models, don't sacrifice on account of money... taking the plunge is cheaper in the end and you'll never have a regret.
Good Luck!
P.S.~ I spent two years at a very reputable junior college and living at home... now I'm two years behind in college! I suggest spending one year at a junior college to take gen eds and make sure you're positive about your major and then getting on with life. Not only is living on a university campus one of the most defining/challenging (and ridiculously fun) times in life, but it helped my grades... Even in an honors program where exam scores curve below failing, school has gotten easier just for the fact that I'm finally out on my own doing something really difficult and it's incredibly motivating. Staying at home in a junior college can start to feel like a 5th and 6th year of high school pretty quick and motivation becomes stagnant. Then again, that could just be me!