Hi!
I just recently (yesterday) ordered my first Mac -- an 8-core Mac Pro. (I've used Macs for years but have never owned one.) While it only has 2GB RAM now, I will probably move to 6GB in a week, and more later.

I am planning to use Boot Camp (to directly boot to another OS when necessary) and I've also purchased a copy of VMWare Fusion (for when emulation is fine).

Can you help me decide what version of Windows I should install? What are the key considerations for choosing one over the other?

Relevant info:
1) I don't currently own a spare license of any of the above operating systems, though I do have XP Pro (32-bit) on other PCs.
2) I'm planning to switch over to native Mac programs I currently use (e.g., Photoshop, Dreamweaver). So... I won't need to transfer my copy of CS2 for the PC to the Mac. (Though would this result in a speed gain?)
3) I will be doing work on audio files. I've heard Vista can be kind of messy with respect to audio performance.
4) In the (near) future, I will be editing HD video, though I don't currently own any software for that on the PC, so I might as well go straight to Mac versions.

Any arguments for one version over another? I'm inclined to think a 64-bit OS will be best given the 64-bit processors...but maybe it doesn't matter as any software I'd run will probably only be 32-bit (for now).

Also, the 64-bit OS's are a bit more expensive.

Thanks for any thoughts you have to help me make a decision.

Edit to add: In case it's relevant (eg for drivers), I did order the Apple Wireless card (or, rather, chip) and the NVIDIA 8800. Everything else is standard.

When I do my audio work, I will use an outboard analog-digital converter. I've not decided on what else I'll use/need. I know the EMU 1616M solutions involve a card that only has Windows drivers, but the fact that it uses a CAT-V connection to a (far-away) A/D converter is appealing. I'd prefer to use something with Mac drivers. I don't really need advice on that in this thread (I'm open to it but don't want to dilute the thread); I only mention it in case it influences thoughts on the version of Windows to install. I imagine the device would not be accessible if running in Windows emulation mode.