win 7 should easily work on ur build, but i will warn you, it isnt quite finished.
i have used it from the release of the RC, and to be honest it isnt quite as stable as Vist as yet.
people will hate me for saying this but, atm, Vista would be a better choice becouse of stability and compatibility.
win 7 is tempremental on some software packages, and games and does not like google chrome at all.
but when Win 7 is complete, then swap as soon as poss.
PS, dont take this the wrong way, win 7 is the way to go, and apart from a few issues, it has to be an amazing opp system in features and looks, also the speed is like XP with a sweat Vista look.
but atm if ur a gamer, Vista would be more benificial untill the new opp system is available and tested for a few months.
Win7 so far is cool but to run it as your primary operating system, theres flat no way I'd do that, this software is still in its testing phase there are many more bugs to be discovered and dealt with by Microsoft before its ready to be canned and shipped.
Most all AV software is still in BETA testing, some drivers are still BETA drivers, even though you can use Vista drivers if Win7 drivers are not available, its still a risky proposition to even consider using this OP/SYS as your primary operating.
What the hell, I'll play devil's advocate. I say go with Win 7 RC and put that money saved from Vista into your hardware. I have been using Win 7 on two systems with little to no trouble. The real issue I see here is spending money now on a license for Vista when the release of Windows 7 really isn't very far off.
I have Win 7 rc x64 on my new build and am generally VERY happy with it.
However, it is NOT as stable as a production release and, from what I have read elsewhere, seems to be a little less stable than the Beta release.
In practice, this may make sense. For the beta, Microsoft released everything that they had finished and were primarily concerned with checking for useability issues that would require changes to the functionality. Then, for the RC, they made changes to the functionality and added some other features that had not been ready for the beta. For the RC, they are only really concerned with fixing bugs and so the RTM will probably have the same functionality and features, but will have the main bugs fixed. Thus, they went from a stable 95% solution to a less stable 100% solution, I suspect.
In your case, assuming that this is genuinely for a gaming machine and does not have anything which would cause problems if it got lost, I would recommend using Windows 7 RC. It is generally fine and avoids the risk of paying $100 for Vista only to then need to pay another $100 for Windows 7 when it is finally released. Of course, if Microsoft would extract its head from its tuchus and advertize that upgrades from Vista bought from now on would only cost $10, the decision might be different.