Hi, I made the exact same decision as you! I'm skipping Vista completely and installed XP Pro x64, Service Pack 3. So far I'm loving it and haven't run into many issues. I'm a 3d artist, and all of my software runs on it just fine, [3ds Max, Maya, Photoshop, Flash, ZBrush, etc.] Some 3d applications even have superior 64-bit versions available. Going over 4 gigs may seem unnecessary for some users, but for my line of work it's nothing short of a lifesaver.

As for games, I've successfully used various free MMOs, and Guild Wars, and ran Steam, absolutely no problems. Most modern games should work seamlessly, you might only experience problems with much older games, like Diablo.

The only issues you might run into are drivers for external hardware devices i.e. printers, scanners, graphics tablet, wireless keyboard/mouse, etc. You'll have to do some hunting online, but I was able to find workable drivers for all of my peripherals. The only problem I had was my Wacom Tablet and a logitech wireless mouse/keyboard combo. Oddly enough, each worked fine separately, but when both were installed it caused problems - I had to forfeit the wireless mouse for my much more beloved tablet, in the end. But if you don't own a tablet, this will not be a problem you'll be facing. :)

There were only two pieces of software I could not install due to compatibility issues, and both are relatively unimportant, in my opinion. The first was Norton - which honestly one can do without, there are countless comparable antivirus programs, and generally for better price tags. The second was Itunes, which is a little program I personally hate. :) The newest version of Winamp can sync to an Ipod, so this solves that problem as well.

There's also a lot of help from other users out there on the Internet, and almost any problem you'll run into has probably happened to someone else before.

The upgrade is probably not worth it. The 64 bit version of windows simply provides a 64 bit platform for applications to take advantage of additional processor capabilities. However, even as long as x64 has been around, applications in general are still not leveraging the platform and benefits are marginal at best. Most of your programs will probably continue to run in 32 bit mode, even on a 64 bit OS. And there's a chance that some of them may not run at all. The only real advantage of a 64 bit system is that it can go above XPx32's 4GB RAM limit. But for most users going above that is silly, if your motherboard even supports it. You'd be wiser to invest in a better graphics card, processor or FASTER RAM vs more RAM.

Many of your games will probably run fine on Windows x64. Windows x64 can usually do a pretty good job at running x64 and x32 bit applications, but it cannot run x16 bit applications, like Windows x32 can. So if you use a lot of older programs or play a lot of older games, you may have some issues. The other issue is this: Windows XP x64 was Microsofts first attempt at a 64 bit OS. Because of this, Windows XP x64 is known to have a lot of problems. Many people who wanted a 64 bit OS moved to Windows Vista. If you absolutely refues to go to Vista (they fixed it, really), I would suggest waiting for Windows 7 x64. The official Windows 7 Beta is available to Microsoft TechNet and MSDN members right now, with the beta available to everyone else in 2 days. I recommend installing the beta if you want 64 bit OS now, and waiting for the final version of Windows 7 to be released. I also recommend dual-booting Windows what ever you decide x64 with your XP Pro x32 for the best of both worlds. As far as if it can be done, it sounds like your computer is capable of running a 64 bit OS. However, you problably won't see a speed increase unless you plan to take advantage of a ton of RAM. A 32 bit OS can fully support up to 3GB of RAM (they officially support 4GB, but they start reserving it in a weird way). So, unless you plan to run more than 3-4 GB of RAM, you probably won't see a performance benefit by upgrading to a 64 bit OS.

I would second profexorgeek's answer except that I would add that Adobe Flash will not run in 64 bit operation but will in 32 bit mode

I'd just wait for Windows 7 to be released Microsoft just announced at CES that it will be released on July 1, 2009 the public beta is being released soon.

Sent from: my Vista 64-bit machine