if it is prebuilt there are some possible problems you may come up to:
as you say, OS bound to mobo, but if that happens spout crap to microsoft about how you RMAed your system and it turned out that the mobo was faulty so they replaced it but didn't give you a new vista key and it is saying that this one is now not working. Microsoft will disable your old key, give you a new one and that will work. It should work anyway, I have taken the vista key off of an old desktop I had and put in on a new laptop hard drive when it broke and it worked fine, 9 times out of 10 it has no problems.
Didnt know that...thanks...been having issues with HP anyway, already swapped mobo once..how long it take MS to help you with new key??
if you go to i7, you will need to bare a couple of things in mind. First you will need a new power supply because the i7 use alot more power than a core2duo will, especially one clocked as low as yours. The power supplies that come with prebuilt systems, especially ones like hp, dell etc are good enough for the system you are given, but you upgrade slightly and they won't have the power to run it.
think i have 500w power supply, have nvidia GT8600GT card...how can i know what wattage ps i have? look on ps?
Second, I would wait for the i5 to come out because they are supposed to be as if not more powerful than an i7 920 and cheaper too......didnt know that, thanks
A thought occured while typing this too, you aren't planning on wiping your hard drive when you get a new mobo are you? So long as you keep the hard drive unformatted then there whouldn't be an issue with Vista not wanting to play with the key you gave it....Im confused, dont understand what u mean?