Handheld PC / GPS Receiver

I just bought on of these for fun, and it is a fantastic toy. It can tell me how to get to all the places I already know ! It even knows where my Mum lives - freaky :-)

Anyway, is anyone an expert/user on these PDA thingies (can I use CCleaner on it ?)

(and a good link to free PDA software would be nice)

Oh, and an alternative to this MS ActiveSync (Koi-Karp) rubbish.

Thanks,

B.