I also use a Wiimote with FreeTrack 2.2. The FreeTrack folks have documented that the Wiimote IR camera puts a much lower load on the processor than a web cam does. I won't opine that FreeTrack with a Wiimote is just as good as a TrackIR because I don't have a TrackIR to compare to. I will venture that based upon a comparison of the TrackIR's camera specs vs the Wiimote's, that a properly adjusted FreeTrack 2.2 using a Wiimote should be entirely acceptable.
As for the touch screen emulation via IR LED and a Wiimote, I've been contemplating that since seeing it on Urze's project list. Johnny Lee Chung deserves all the kudos that he gets for his breakthrough work with Wiimote IR cameras.
Prior to seeing JonK's thread here, I was thinking that I would locate the activation switch differently. My first thought was to put a switch on the middle finger tip pad, such that it could be activated by the thumb while pointing the index finger (with the IR LED mounted upon it) at the screen. That should allow the IR LED to be right on the tip of the finger, hopefully yielding good, repeatable accuracy.
I'm running this on an Acer Aspire 8920 laptop (gorgeous screen!), so I'm hoping that I might be able to get this to where I would just get the LED close to the screen, but not quite touching it. ( Of course, that probably won't hold up too well in practice, when I'm getting shot at... ;) )
I have some other possible refinements that I want to ponder and possibly pursue. If anything good comes out of that, I'll definitely post something.
Regarding the use of Wiimote(s) with a PC, be aware that Bluetooth stacks can be a *major* issue. My Acer Aspire has Bluetooth built in. While the included Bluetooth stack appeared to yield a "connection", it did not achieve useable communications with the Wiimote. (Vista 64 bit, BTW). The only stack that worked in my case was BlueSoliel... so there was a bit of extra expense that I hadn't anticipated. If you're buying a Bluetooth dongle to add Bluetooth to your computer, I would definitely recommend looking for one that includes the BlueSoliel stack.
As for using a single Wiimote to handle both FreeTrack and touch screen emulation, I don't see how the FreeTrack software would be compatible with that. In my opinion, you would need to write new software, and it would not be a trivial undertaking. By the time you got done with it, the expense of a second Wiimote would look miniscule (if you value your time at all).
JonK... specifically which program(s) are you using from http://www.cs.cmu.edu/~johnny/projects/wii/ ??
Thanks!