Thought I'd share, for the edification of the masses.
I just installed XP on a new SSD, got the latest drivers etc, fired up Spiral Knights and it was all wonky. Mooshed text, rendering artifacts.
ATI's 11.4 driver is a known issue here, so I followed instructions and went down to 11.2.
Still wonky.
Booted to the old HD's XP, checked out what my driver there was, the one that worked.
9.12
>_>
So now my new SSD has ATI's 9.12 and everything is great. Lesson? If in doubt, keep rolling back!
I was running the game fine on like 8.something before updating to 11.4 and then rolling back to 11.2.