It looks like Valentin has both answered Thomas' question, and diagnosed Andy's problem, in the same post. Well done.
Andy - I don't have XP to
test on, so I'm just guessing. Do you get the same message when you type "javac" that you would when you type any unrecognized
string, e.g. "javab" or "qwyjibo"? If so, I'd concentrate on the system path rather than class path. But I don't have much else to offer - sorry...