I'm stuck between battery life and performance here. I dunno which one I should get, so I guess you shall decide. Both of them cost $599, one has good performance, one has good battery life.

ASUS UL20A-A1
12.1" 1280x800
Core 2 Duo SU7300 1.3 GHz
250 GB HDD
2 GB DDR2
Intel GMA 4500MHD
6-Cell battery with about 7 hours of battery life
Or...

ASUS K50AB-X2A
15.6" 1366x768
AMD Turion X2 RM-75 2.2 GHz
320 GB HDD
4 GB DDR2
ATi Mobility Radeon 4570 w/ 512 MB GDDR2 VRAM
6-Cell battery with about 1-2 hours of battery life
It's up to you, I honestly can't make up my choice. Choose my laptop for me.
Poll will run for only one day.
Oh, I should mention that I need this for school, but I want to also use it to be able to play some modern games.