Dual boot problem

Hello, i have a Windows Xp and Windows Vista installed on two diffrent hard
disk. Windows Vista installem "Primary Master" while Windows Xp is installed
on "Secondary Master". Whatever i installt last i am able to boot only to the
last installed windows. I had xp, i installed vista, then the dual boot
window didnot show up and automatically got booted in vista. the i formatted
the secondary master and installed fresh copy of xp and now it boots directly
into XP.

I needed to use start up fix problems(recovery options) in windows vista
dvd. then i was able to access vista only. then i used FIXBOOT in xp cdrom
and now i am able to boot only to windows xp. PLease help me. i am a novice
with boot management but otherwise know lil bit of windows.

PLease Help!!