The build 6000 is the final retail release. What interests me here is that you say it worked fine until you re-installed Vista. If this is the case then perhaps it wasn't a clean install? Its very rare to get a buggered disk and as you have said it initially worked fine I'm thinking that the disk is ok. If you only have a index score of 1 then Aero will not work as it needs a score of at least 3 to do so. This is probably why the chess game is giving you problems although it says it only needs a index score of 1 to run.
Ok, so possibilities, have you actually run the index score wizard? You will only have a score of 1 untill you do so. 1 It may as I said above need a 'clean install' so try installing Vista again.2 Is the HDD ok? Are you running a RAID set up? 3 You say the RAM works fine 'together' but have you tried running them seperately? This is the only way to determine if one's buggered (although you could try running Memtest86 you can get it here
Memtest86+ - Advanced Memory Diagnostic Tool) I know I keep harping on about this but it really is a strong possiblity. Let me know how things turn out and good luck.