1) Wireless NIC -
2) Wireless Access Point(AP) -
3) If you plan on using active synch - you will first need to have a partnership setup, (you did this when you connected the PPC to the desktop, hopefully)
4) You will need to configure the AP and NIC.
After that it depends on what hardware you get and what setings you desire. The links above are suggestions only. I use them, but they by no means speak for everyone.
-brnt out