Ok, a couple 1% 100k and 10k resistors plus some caps later, I have a working instrumentation amplifier with gain control! There is some offset error, but I can get rid of that by changing the pot on the bridge...This has been really helpful, thanks everyone!
hey
why don't you write up a tutorial on what you learned, and put it in the Playground? It would be useful to other users down the line 
D