Just purchased this OS aand wonder about it's wonders. Also AMD X2 4600 Dual Core and Gigabyte board, and Matrox APve.
Found out it will handle 128 gig of ram and there is an exchange program for a possible free upgrade to the end of July.
Using it on one system, not seeing any benefit in terms of speed just yet, but only have a couple apps that are 64 bit ready, and neither of them are loaded on that machine.
Using in on a Dell 670 dual Xeon processors. Works like a charm. Very few issues that I can't work around, e.g. waiting for the drivers for my ink jet printer and scanner.
So far, Vegas is happily utilizing both processors and eating up my 6gb of RAM without any problems.
Was using Premier Pro but Adobe's products don't want to recognize my DVD burner under x64. DVDa didn't blink an eye.
I just traded up my copy of XP Pro for x64 under the TAP program that Dell had going. Made x64 even better has Dell provided a number of inf files specifically for the 670. Previously was running the evaluation copy that can be download from MS website.