Forget Serial ATA right now, look at the tests done by Tomshardware and others and you'll see that it ain't impressive right now. The important thing we need is to get OS4 taking advantage of 'ballpark' hardware now. As soon as it's sold in reasonable figures (ie more that none ;~) expect advances to come thick and fast.
All the hard core AGP, DDR etc only apply to either serious gamers and video professionals. The average computer user will not necessarily see a reason for any extras thrown at them.
-john
