I do not see any glarring mistakes. In fact it looks more or less just like most of the ones I have done, except I take this line out dhcpd auto_config outside but I do not think it matters really.
Are you getting addresses from the PIX in DHCP mode at all? As in when you look at the PC using ipconfig or winipcfg, do you see the correct settings after it gets its info from DHCP? I only ask because if there is another DCHP server on the network, or if they are not even requesting from the PIX, then that may be an issue you need to resolve first.
Also, and I know it sounds so lame out loud, but have you power cycled the PIX since you did this config? Sometimes that helps alot. I can clear caches and buffers all day, and no dice, but one reset and it works great. Maybe cisco is owned secretly my M$? No, that would be silly. But try the reset anyways, unless you did not save your config, it cannot hurt.
Eddie Venus