They must be on separate partitions. And do the 32-bit first.
For more on dual and multiple boot scenarios with x64 Edition (or any
others, actually), you might find the detailed blog I did on this of
interest and use.
http://msmvps.com/xperts64/archive/2.../21/76180.aspx
HTH.
--
Charlie.
http://msmvps.com/xperts64
"Robert" <> wrote in message
news:6cydnRiIOPPYc6XYnZ2dnUVZ_u-...
> I'm building a dual boot system I hope, based on raid 0 150gig raptors (1
> array) to share 32 & 64 bit os. The primary os is xp 32bit pro. Does
> putting both os's on the same drive (array) cause any problems? should i
> split the drives, one per os?
>