are you using same webcam than before or other "integrated" webcam ?
Vista drivers are different than before ... Perhaps vista webcam driver of your logitech are not too good ...
Have you disable all "Auto" features" of your webcam driver (have you disable fluo light 50 Hz - 60 hz ?)
Freetrack must be run with administrator right (you must check box "administrator" on freetrack.exe properties ...
You must disable all others webcam applications .. (like MSN Live messenger) !
In last, try to change vidéo compressor type and resolution of your webcam to increase FPS ...
Ensure interpolation are correctly configured on freetrack GUI ...
Have you SP1 on Windows Vista and last DirectX 9.0c update !
Because Vista use directX 9.0 (L) and DirectX 10 ... And vista default directX 9 can be update ...
here you can find last official directx 9.0c for Vista (in english - check your OS language please before install it) :
http://www.microsoft.com/downloads/details.aspx?familyid=2da43d38-db71-4c1b-bc6a-9b6652cd92a3&displaylang=en
If there is no issue for you after that ... Try to made a forum search about good webcam frame rate in windows Vista, or webcam for windows Vista ...