You will need to update your BIOS first, since the board needs the most recent BIOS version (1502) to even support the E8600.http://www.asus.com/products.aspx?l1=3&l2=11&l3=397&model=1459&modelmenu=1
Click on the "Downloads" tab on the left column, and it will ask for which OS you're using (Vista 32 or 64 bit), then give you a list of downloads. There's even a tab on how to upgrade the BIOS if you're unsure.
You won't have to re-install Vista, but you'll probably have to re-activate over the phone as Vista interprets a BIOS update as a new motherboard installation. It's quick, but annoying - just tell them you upgraded your BIOS and they'll read off new activation numbers to you. (This is probably the thing I hate most about Vista.)
I do recommend that you upgrade your motherboard's chipset/audio/etc. drivers while you're at it.