I can’t believe I didn’t realize this but there’s a free RADIUS server for Linux from FreeRadius. And Windows 2000 and Windows 2003 both contain a RADIUS server. So, if you’re already running one of these, why not switch over to WPA Enterprise? There’s gotta be a free one available for Windows XP, doesn’t there? I just don’t know of one at this time but I’ll keep looking. And if you know of one, please let me know.
BTW, I got some of this information from this article but I don’t agree with everything he says in it — I mean, I was taught was that real security is all about layering your security and, if you’re running a small network, why not include MAC address filtering and SSID masking?
Update: FreeRADIUS.net has a Win32 distribution of FreeRADIUS built from the original FreeRADIUS sources using Cygwin.