Yes you can. Just do it as three completely independent installs (plug out the other drives when installing if you want to be sure) so that nothing messes with anything else and by the time you have the new XP done you can throw the old one physically to the bin. You might even be able to mirror the old drive entirely onto the new one and be done with it once for all - if you do it and it blows right onto your face it wasn't me who said it! But going the orthodox way, of course you can. It'll take quite a bit of work to install all the programs (on the other hand you can skip the ones you never used after installing and trying them out to notice that they sucked) but copying the actual files over is a piece of cake, a time consuming one but still.
Whether you'll need 32 or 64 bit is up to the choice of preferring everything certainly working like it always did or being able to use more RAM. Personally I'd go the 32 bit route as during the nine years of using XP I've managed to run out of RAM exactly once and when it happened I had several 2048x2048 texture files with a couple of dozen layers each under construction. The ~3.25GB that 32 bit can cope with is a lot and then some for XP. And you'll have that W7 64 bit anyway so you can do the seriously heavy work with it if need arises.
Acronis TrueImage seems well thought of (payware, 30-day free trial.....) but whatever you use, make sure you verify the result to make sure it's worked properly.