it's mostly when i keep instant messengers connected on mine that it dies, but if you're using it a lot the screen itself would be a big draw. honestly, if you're at school, you must have a bag you can throw an extra battery in? it's a good $10 investment. i always bring a spare when I go to parties or whatever so I don't get stranded anywhere with no phone!

Try reading up on the overclocking, and set your phone to run around 805 mhz with one of the ideal or ulv profiles, and try enabling smartreflex. It doesn't work for everyone, but now is the time to mess with that stuff, when the device is new, so any problems don't erase too much if something gets messed up. That should reduce battery usage though, and is pretty safe.