10mbps is what you should be getting over usb. You can check your device manager, to make sure the device isn't disabled, if its not try deleting it and let windows rediscover it. You can also deactivate activesync, on both your ppc and pc. If your using vista it shouldn't require any drivers at all, if your using xp it needs active sync to be installed. One last thing u can and should do is make sure that your registry doesn't have remnants of the old entries. you can go to
www.ccleaner.com and download that, it's free and works like a charm. I swear by the program, just scan for issues, it has an icon that looks like the registry editor logo then reboot and try again. Good Luck!