Upgrading to WinXP 64 a good idea?

I'm buying a new computer to replace my 8-yr old one. The new computer I plan on getting will have a quad processor (64-bit) with 4GB RAM. Unfortunately, the new machines only come with Vista which I'm trying to avoid converting over to for now. Since I'm getting a decent size HD, I'm thinking of doing the following: partitioning the HD into 3 "drives". I plan on keeping Vista on C:drive and thinking of installing Win XP Pro x64 on D:drive so I have the option of booting up Vista or XP-64 with the intent of using mostly WinXP 64 until I gradually transition over to Vista over the next few years.

My question is the following. I currently have the 32-bit Windows XP standard/home version on my current computer - so I'm going to have to buy the WinXP 64-bit version which is fine. I want to use the 64-bit version so I can fully benefit from my new hardware - but what about all my software programs that were purchased years ago that are 32-bit based apps? Will they run on Win XP Pro 64-bit version or will I encounter problems? And if they DO run on WinXP Pro64, will they benefit from the upgraded hardware or will the capacity be limited to 32-bit? I also have some peripherals which I believe have drivers that support 32-bit not 64-bit. If I can't find drivers for 64-bit, will those be rendered useless?  If so, would I be better off using a standard Win XP version (32-bit) until I convert to Vista sometime down the road? But if I do that, then I won't benefit from the new computer hardware's capabilities, right?

Thanks for your help.

Your 32-bit applications will run just fine on 64-bit Windows.  The applications will not directly benefit, as they willl still run in 32-bit mode, however, Windows x64 has better memory management, so on that fact alone they might run slightly (1-3%) faster.  Running x64 is the only way your going to have access to all 4gb of RAM in that system.

I think having 3 OS's on one machine is a little overkill, especially since they are all different Windows versions!  It seems to me like it is just a huge waste of space. I would reccomend just going with Vista x64 and if you want XP, going with 32-bit XP.  Odds are, if your hardware and software it is going to work in XP x64, it's going to be just fine in Vista x64.  In fact, I find that some hardware has Vista x64 drivers, but no XP x64 drivers.

Ryan, thanks very much for your reply. I've decided to install WinXP 32-bit on the other drive and just run that until the manufacturers of my hardware catch up with 64-bit drivers and then I'll switch to Vista. Hopefully by then, MS will have improved the Vista OS :-)

Thanks!

Just so you know, Vista has become pretty mature since its launch.  Remember, it's been out over a year now!  It's even at SP1.  It would run great on that high powered system that you just got :).

Yes, I know! - only problem is half my hardware still hasn't updated their drivers to support Vista or 64-bit for that matter. I'm going to keep Vista-64 on my machine on another drive and play around with it... while I continue to use XP (32-bit) for my everyday work.

Thanks for all the help :)