I'm sure this has been asked before, but I didn't see what I needed.
I have a computer, [new this year,] with 'Vista Home Premium' on it.
I partitioned the 'C' drive successfully and have installed 'XP' on what is now drive 'E'.
I do remember reading that installing an earlier version of Windows may cause the later one not to start.
I do have 3 rescue disks of 'Vista', and have re-installed Vista successfully back on 'C' drive.
My partition of 'E' drive is still in tact, and it seems that nothing is disturbed by the re-installation of Vista, and I'll bet that 'XP' is still on there.
What I don't know how to do, is to have the dual boot option.
When I followed the advice in the Windows Help, only Vista showed up as the default OS option.
I'm guessing there may not be much more that I have to do.