Are you sure you only have 512 MB RAM? That’s not enough to run vista. I suppose Linux might work, but win-xp or vista--no way! I did a quick search for Linux installs and here's a link with some configuration information http://www.phoronix.com/scan.php?page=article&item=457&num=1 .
I suspect that only win-xp or vista will have all the drivers available at this time for all the additional hardware you want to add, but you can do a Google search to see what is available for linux. Also, you can check with Nivida (i.e., their web site) for the latest mother board drivers. Since you bought a license for vista, you should be able to get back to your supplier and usually for $10/$20 (us) more you can get the release on dvd. Of course, after installing vista, you must install the drivers for the mother board electronics followed by a reboot of your machine. You’ll need at least 2 gigs of RAM to run vista (1 gig for xp), and probably at least 256 megs of video memory (which is integrated on your mother board). Make sure you pull out the Ethernet card before doing the install, since you’ll no doubt want to use the onboard Ethernet electronics. Remember that your board electronics won’t be fully working (e.g., you'll get a low-resolution display) until you install the mother board drivers (did you get a install disk for this?).
Hope this helps,
Cyber