The Missing Sync is a piece of software for OS X to let you sync your PIM information with your mobile device, like a phone or a PDA, that's not supported natively with OS X. If you have a WM5 device, go grab the Missing Sync 2.5 beta and sync up your Pocket PC.
Bit of caution though. This is still beta, so if anything goes wrong, your contacts/calendars may be wiped out. You may want to back them up first, since your wife would be pretty angry if you forgot your anniversary due to "software error".