You are mostly there. To do what you want,
1. Get a wireless CompactFlash for your PocketPC (I've used Socket and
NetGear and they both work well)
2. Get a wireless NIC (PCMCIA/PC Card) for your notebook
3. Get a wireless access point/router. I have the LinkSys BEFW11S4 and that
gives me 4 ethernet ports for standard Ethernet devices, and support for
wireless devices too. There are others out there, but I've had good
experience with the LinkSys ( http://www.yqcomputer.com/
the official link but the one Google put at the top for me).
As for how you hook it up... By far the easiest is to hook up the cable
modem to the "WAN" jack in the back and then hook up your desktop to one of
the 4 ethernet ports. (Your desktop isn't wireless when you connect it this
way.) The built-in NAT firewall (technically an oxymoron, but that's what
everyone calls it) is very secure -- too secure in fact, in that you may
need to tweak some of the access point/router's port settings for some
applications which need to talk to your home LAN.
This is essentially what I do at home and it works great. There are other
ways to connect it, but this is the simplest IMO.
By the way, I wouldn't mess with WEP encoding, it's kind of a pain and it's
not very secure. For your setup, using the admin interface of the access
point/router, you can set up the device to only connect via specific MAC
addresses (your notebook and pocketpc adapters, 1 & 2 above) by setting up