Laptop. Well, maybe not so much anymore, but it was wonderful as a student. For my marketing internship I did a lot of web design and made other print media. The company didn't have a computer I thought was good enough, so I used my own laptop and software programs and just tapped into their network and printing system. At home, I did most of my school work on the floor or on my bed, I hate sitting at my desk for long b/c I have bad posture. It's also nice b/c I can share pics and music with my family by taking the laptop home and connecting it to their network. I like the keyboard on the laptop. I like the LCD screen b/c I have bad eyes and frequent headaches, but you can still connect a larger monitor or CRT to a laptop at any time.
My laptop has given me the most bang for the buck. I bought it for only $200 and have spent just $20 for a wireless card and then $60 earlier this year for a new hard drive (3x bigger). I've had the laptop for years and it was 4 years old when I bought it. It does everything that I need and has performed WELL above my expectations.