Ive always said....
If you have to ask whether its any good or not, then its not worth it.
I got XP64 also. I have tried it on various PCs of mine, and its no faster or slower than plain XP. A few things have issues, such as some TV Cards, and IDE or RAID Cards, but this is improving by the minute.
pretty much every game will run on it. All mine certainly do, even the most obscure DOS games are perfect.
One thing I have noticed however, and that is, that if any program does something during Windows' startup... The DOS-type bit, then that program wont work.
I mean, say Partition Magic 8 work absolutely perfectly if it can do its task without havign to restart to do it.... So, I can say, work on D: and above, providing there is no Page File on those partitions, and I can make C: bigger, but not smaller.
PageDefrag also does not work either which is a shame.
Also, while there are some hacks that I know of to mount ISO images as virtual CDs, there is no way to do it properly ( Virtual CD which I dont have perhaps? )
Anyway, I have settled on having XP64 on my DFI LanParty UT 250GB & ClawHammer 3700 and its absolutely fabulous on that. I did try it on my P4 3.6 and x2 4400, and even the Sempron3100, but settled on the Claw mostly because I am only really using that for Video encoding, and I was rather hoping that XP64 would help it, but it does not.
In my honest opinion, using XP64 as a main OS may very well be a mistake, especially if you have no other option. Basic XP runs 100% of software, has 100% support for hardware, and is well, 100% everything, and while XP64 is a good 80% there, there is a good chance, that you will have or need something that falls into that other 20%
