upgrading motherboard

Am thinking of getting a new motherboard, have at present nforce 4 ( ecs ) a939 motherboard and 64 bit home premium vista oem os. Seen somewhere that getting a new motherboard would invalidate the vista, is this true and can anything be done about it, also any decent motherboards out there, am thinking of gaming and home video editing etc.

What do you want a new motherboard for?
As in, why do you want to upgrade?
And what's your budget, and the rest of your system?