I'm running a dual boot with Vista Home Premium and XP MCE on my XPS 410. It is working out very good. I used Vista Boot Pro for my boot manager. Go check out their web site http://www.vistabootpro.org/
and it's pretty straight forward.
I initially installed Vista and got all the drivers and updates working. After that I used the Vista's disk management to shrink the drive. I created another drive with the unallocated disk space and formatted it.
After formatting the space, I rebooted and installed XP. I installed XP into the newly created drive. From there on out your computer will boot to XP. Apply all the necessary updates and install the drivers.
Install Vista Boot Pro and follow their instructions. It's worked out great. Only problem now is that I have two operating systems to maintain.