My work chair...

My major complaint about my new job is that I hate my chair. Weird, and probably good that it isn't something worse, I know, but I have some fairly annoying back problems and my chair makes my back pain so much worse.
So after talking to some people about it, I decided to try a pillow. First I'm going to try a pillow you sit on, and if that doesn't improve things (by raising me up so the part of the chair that currently is digging into my shoulders awkwardly is instead supporting beneath them) I'll try a lumbar support pillow.

Have you guys tried these from Brookstones? Have you liked them?

Tempur-pedic Seat Cushion

Nap Form Mini Lumbar

For now I've gotten something like this to sit on... lets hope it works!

Target Decorative pillow

Because if this doesn't work, damn. It will be no good, and my poor pregnant massage therapist will have to see me more than my normal twice a month (I told you my back has problems) and that could get seriously expensive.
Anyone have any work chair/back pillow suggestions?