There is the Wiimote/freetrack/IR trackclip solution as well Joe, if you have a Wii its near cost free, and 100fps.
Wiimote has hardware ir tracking of up to 4 points.
Two gotchas though, you need a compatible bluetooth dongle and stack ( under XP/Vista this can be a PITA, under Windows 7 the default bluetooth stack works a dream ). The other gotcha is, Naturalpoint embedded protection into their API for a while now, and whilst workarounds exist for games written to support the later versions of their API’s, it can be a bit of a black art. This is not a problem in IL2 however.
I have come across a method of using an early TIR unit in conjunction with Freetrack to enable 6DOF/ multiple point tracking but haven’t been able to remember the URL ( and it was a few system rebuilds ago so not in history )
Sporran