Yeah. You shouldn't need anything else. If you've got a recentish version of Windows then you can just use Internet Connection Sharing (ICS) You'll need to have this computer on all the time you want to use the iPaq wireless though. If you don't want to have it on then you'll have to buy an access point to replace it.

Most wireless equipment allows you to operate in two modes. Infrastructure which requires access points and adhoc which does a sort of peer to peer arrangement with the computers.