From what I understand ...Version 1 (the Red UI) won't run on Vista.......updating Gearbox won't do a thing but make it worse.....as "RiffTracker" runs with the old GuitarPort 2.5 software that is now obsolete. You should be able to get it working with XP as your OS......just don't upgrade to Gearbox.....unless you also upgrade to version 2 which is well worth all the new features.....then you could Riffcast, Rifflink and tons of new features as well.........
you can find how to upgrade here...........
Upgrade another option would be to get RiffWorks T4 which is free.....and is a watered down version of Version 2.......that will work with your GuitarPort but you will have to install the Line 6 Monkey and upgrade to GearBox software all for free...........
You can get T4 here..........
http://www.sonomawireworks.com/T4/