I need a laptop for school so I need to part with my 20 inch iMac monster.

The specs are

2ghz ppc
1gb ram
20inch lcd (no dead pixels)
400gb hdd (374 actual gb)
keyboard and mouse
loads of software haven't decided if I should wipe the drive clean or not

How much could I get for that?

Then, with that in mind, I can add five hundred for a laptop. For a laptop, I need something that will last 3 years. I am a philosophy, classic, and religious studies major so I mainly surf the web, write essays, e-mail, IRC, adiumx, and occasionally use mathematica.

What should I get? What could I get? I know I want an Airport card (which means I have to buy a new router -- oh well). I need something that will last for three years (I'll buy something before I start grad school). Oh, i will buy an external HDD to store all my extra documents so HDD space isn't a priority.



Addendum: I don't *really* need a laptop until August, but some online classes I am taking this summer would benefit from the laptop...

Please, any suggestions : )