Chair Help!

I am a 22 year old college student who spends a lot of time on the computer. Anymore, I can't sit in one position for more than 10 minutes without fidgeting or repositioning myself due to pain in my lower back and hips. The computer chair I currently have is an old office chair that sits at a plain 90 degree angle, not the most conducive for posture at all!
I was hoping someone has a suggestion for a good office chair that can be sat in for extended periods of time. I am a small person, 5'2, 125 pounds, so a lot of office chairs don't fit me at all, and I'm left with my feet dangling if I sit all the way back in them. I looked into kneeling chairs and these chairs that are nothing more than giant yoga balls on a base, but I wanted suggestions from others before buying anything.

I thank you in advance!

[Katelynmom]

I just got a new chair for work but unfortunately it was $414 which is high for a personal purchase.  I would look at the Ergo chairs (K-log or Herman Miller).  With chairs you get what you pay for!

[Karabu]

bump?