I'm not really sure.
Windows XP was known to almost never work when swapping motherboards (but CPU's were normally okay). Yet now with Winodws 7, you can swap nearly anything and it'll work. Some people still say that you can't do it safely, but I had Win7 installed on an old system and then one day put that HDD into a COMPLETELY new system.. new motherboard with new chipset, new processor, new ram, new GPUs.. everything.. and it worked just fine.
Unfortunately though, I don't know whether vista will perform like XP or more like Win7.
I had once managed to install a new motherboard on XP without the need for formatting or repairing my windows installation. My advise would be to back up all your data anyway, and then just try it out.
Chances are that it would probably work.
Just my thoughts :].