Downgrade iOS 5.1 on my iPad to iOS 5.0
Apple is still signing iOS 5.0.1. You will need to download the 5.0.1 ipfw and then place your device into DFU mode. From there, hold the ALT/OPTION key as you hit the restore button in iTunes. Then point iTunes to the newly downloaded firmware. 

You must act fast. When Apple closes this window and stops signing the old firmware, it will not be possible to downgrade iOS.