new motherboard

Ok i am planning to swap out my old 650i for a 790i motherboard, i have the DDR3 ready so ram is not a problem, but as i am running vista i do realise that it will void my activation key, but i do have a box copy of vista (unopened, i obtained it from a friend a while back) would i be able to install that over the top of my original install with no problems (both copies are Home Premium)?

I searched google for a definitive answer to no avail, seems microsoft FAQ missed a few tricks...

From what I have heard, Microsoft has loosened up on this. You can call/email support and get a new key or something that will allow you to reinstall.

install windows 7!! miles beta than vista

wont void your activation key. there is an automated telphone line. call it and tell them you current key, and what changes you made to your pc. you will be fine. ive done it many times, takes like 10 minutes

Re-reading this, i am struck by your use of "Copy".

Do you a legal install disk? You say copy of Vista and a box copy.
Are they bootlegs?
If you install a new MB with a new chipset, you will have to reinstall (Microsoft nor the MB manufact. support legacy installs on new equipment and Microsoft only gives customer support to retail versions).
If you reinstall, you will have activate.
In order to activate, you need to verify.
If you can't verify (you have a bootleg) you have to get a bootleg key.

thanks for the help! I'm assuming I ring them after I have made the changes and am at the activation screen?

the 'copy' I have installed is 100% legal as is the box copy (my friend wanted to uprade from xp but changed his mind) it's just as my pc had vista preinstalled the original key would become invalid and wouldn't be able to install that copy again. but hopefully thanks to chem I won't have that problem! if I could just find the damned English customer services number!