virtualizing XP under Linux and remote IE testing

[rpug-vYTEC60ixJUAvxtiuMwx3w at public.gmane.org (Ryan Pugatch)]

Hello all,

I currently have 32 Windows XP machines virtualized on a CentOS machine 
under Xen.  They're used for testing websites under IE (and are accessed 
via RDP).  Unfortunately, I have been having horrible performance issues 
with Windows XP under Xen.  I've emailed the centos-virt list to see if 
anyone has ideas about that.  What I'm hoping to find out from people on 
this list is other suggestions on what to use to virtualize XP under 
Linux or if Xen is what most people are using.  Secondly, I'm curious 
what people use for testing sites under Internet Explorer (my devs all 
use Macs, and I don't want to have them virtualize on their machines). 
Plus, they need to be able to test under IE6 and IE7/8.

Thanks,

Ryan