Ah the joys of ActiveSync.
You can adjust the AS schedule on your Ipaq to Manual, but that won't help.
You can fiddle with the settings of AS on your PC, but that won't help.
Basically AS is designed to recognise your device immediately and sync with it, and MS have kindly built it to then seemingly continuously want to sync.
Very annoying if you just want to drop in in the cradle so that it is charging.
Many people disconnect the USB cable until they want to Sync.
Others disable AS in the Task manager.
But the simplest way I know is
ActiveSync Toggle, which lets you turn AS on and off on your PC so that it only Syncs when you want it to.
Another option is
Card Export, this is a great program too and when you have it set on the device to Card Export mode (which only takes a tap or two) the PC doesn't recognise it as an AS device and so it doesn't try to Sync. It is a bit faster than AS for transferring files too, and lets you connect to any PC without having to have AS installed on the PC.