Here's the challenge:
Manufacturers have moved on from the Prism2/2.5/3 chipsets addressed by your preferred driver. You'll have a hard time finding a Prism version of some of these cards. Some places may have old stock, but be careful of the version info. The Absolute Value list you mentioned is probably the best source for identifying the specific versions.
Consider a few points:
1. Dump Red Hat. Many vulnerabilities exist in your installation that have been fixed in newer, supported distros. Fedora Core is the "replacement" for RH, if you like that style. Debian-based distributions with some enhanced h/w discovery and GUIs seem to be all the rage - Ubuntu, Knoppix, Mepis.
2. Newer distros will have more recent drivers or something called ndiswrapper which will make more card choices available to you. Many of these could be installed on your RH system, if you chose. By picking the wlan_ng driver first, you're painting yourself into a corner.
3. Get a wireless Ethernet adapter. Sometimes called bridge, these devices plug into a wired Ethernet port on your system and do not require a wireless driver (wired NIC support is almost always less challenging). Configuration is done via a browser over the Ethernet connection. They are more expensive than a PCI card, though.