You'll be able to use your M170 in class - especially if it's a few times a week and you're not spending all day walking around a campus. It's about 9lbs, plus the power adapter is a real brick, and you'll need the adapter if you want to take notes in class. It is lighter than the m7700, but it is still large - as are all 17" models. You can turn the flashing LED lights off, but it will still attract some attention.
It sounds like the M170 or one of the other 17" Pentium M models is a good choice for you. If only the m5700 came with the 7800GTX card...
The m7700 will be more future proof, but it doesn't sound like you need the multitasking capability (e.g. encoding video while gaming, etc).
I saw your thread in the Dell section - some good advice there. I doubt you want to do the 9300 pin mod, so I'd recommend getting the top of the line M170. I think 2.0GHz is plenty for the CPU, but you might as well go for the 2.26. Obviously, you'll want 2GB RAM (can be purchased cheaper from Newegg), and the go7800GTX card.
Good luck with your decision - and don't abandon us. You are still an Alienware owner
