Lovely graphics, and it's very smooth.
What about some baddies though, it might spice it up?
Well that's odd. I'm only using GeneralPath, which should be available in 1.4 and possibly earlier. I have no idea why (or where) it's trying to reference Path2D from.

Path2D is a java 6 thing, it's meant to give float and double versions of GeneralPath. Maybe the jdk6 compiler uses it under the hood, have you tried compiling with java 5?