Well, as I'm educating myself a bit on PDA's, it appears that the PocketPC is the type that I want. I'm inferring that the Windows CE / Windows Mobile 2003 (which it looks like the ipaqs are running now) operating system-based PDA's all come under the PocketPC category.
I've been a little bit nervous about the idea of built-in wi-fi, mostly for future compatibility reasons, but I've got to get over that. I mean, if they are 802.11b, or g, which they appear to be, then those protocols will be around for a while, at least in backwards compatibility mode, and my desired time frame for this to be used and not upgraded is 3-5 years. So, if I can have support for the built-in wireless for 3-5 years, I'll be happy. I'm confident that will happen.
There appear to be two manufacturers of iPaq, compaq and hp. Except, if you go to compaq.com and click on their pocketpc category, you get sent to the hp site. So, I guess hp is the only manufacturer.