Hi I was looking at the read mes that came with it, and they make it sound like its not very compatible with almost everything. I thought Id ask before I went and installed it. Is anyone using it? Does it work without any problems? Will I even notice a difference between it and XP Pro? Thanks Ed.

I've tried WinXP64 on my Athlon64 3500+. Not much of a difference with XP Pro. Some programs come in both 32bit and 64bit versions, e.g. Internet Explorer. For the rest it looks just like XP Pro. Some funny things. Windows Update can only be run from the 32bit version of IE, not the 64bit. Probably has to do with the ActiveX controls that are still 32bit. Poser and Vue both ran smoothly in the WOW64 environment. The performance was equal with WinXP Pro. The main problem with WinXP64 is the lack of hardware support. nVidia chipsets and graphics cards are supported, but at the time of my testing (couple of months ago) ATI graphics cards were not, and neither were VIA chipsets. Some codecs were also not supported. I decided to go back to WinXP Pro until Win64 really takes off with decent support.

I agree with everything svdl said (x64 on 3500+ also). In my case, I use Cinema 4D 64-bit and do 64-bit plugin compiling for it, so I have to stick with WinXP64. I do hate the codec/QT support problem.

For most applications, 64-bit does not make much sense. If you have more than 3 GB of RAM and want to use that amount for a single application, 64 bit is for you. Otherwise it will not make much difference. Using more memory does make sense for some applications, but you would need a 64-bit version to actually take advantage of the bigger memory.