I hope I'm not stepping on any toes but just wanted to add, There are unique upgrades for performance and visuals after outruns. Visuals are hood,rims,vinyl,spoiler ans wide body kit. not sure which order, also only one for each area unlocked. performance mods there are three. unlike NFSU1 you only get one chance at each mod. I've just started playing game again now on PC haven't played for ages on PS2 so memory could be a bit shaky but I think each upgrade takes 5 outrun victories but not sure yet. Hope it helps.
Now for my question. Is there a trainer that unlocks all parts and cars that works with vista as I've downloaded megatrainer and the mouse pointer sticks in the right hand corner of screen.
The trainers on this site are designed for the games, which in turn are designed for specific OS's. Underground 2 was designed for Windows XP, therefore it would be logical to deduct that the trainers are XP-compatible only.
And you could always ask for a trainer for Vista, but this is a 4 year-old game, so I doubt anyone would do so. You can try making your own if you so wish, and we have a few tutorials up here on CHU.