Best solution is to get an exchange account and sync everything (mail, contacts, calendar, tasks) OTA. You can get a free one from mail2web.
Then set the following reg key on your desktop which will prevent any desktop syncing but still allow you to copy files to/from your phone and do other things. It makes your computer treat every WM device hooked up as a guest.
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows CE Services]
"GuestOnly"=dword:00000001
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