I would have thought modern day Amigans would be using a light weight linux distribution + wine + winuae (as it's the best UAE variant)?
Running Windows XP seems a bit overkill when all you need is ALSA+X (+ proprietary video drivers I suppose). Heck you don't even need a window manager really if you're that good...
That would give you a nice hardware abstraction layer, no excess app bloat and should run UAE quite fast without any other processes to worry about.
I guess these days even Amiga users settle for (virtual) Amigas with a bloated OS, having said that I'm half tempted to create a lightweight UAE distro myself

[EDIT]Doh I'd not/read about X-Amiga before writing this post. Please ignore.[/EDIT]