Activesync 4.1 is probably the best bet, I've got in running on my RZ1710 fine, no worries at all so 4.0 and 4.1 are not specifically for wm5! Make sure you uninstall everything, drivers and activesync and re-install activesync, and it will ask you to connect your pda, and it should detect automatically, and it will install drivers for you Failing that, you might have to do a hard reset on your pda, I have done it once before because activesync didn't detect my pda correctly.