I need help before I make a really big mistake. I know that lots may say that I made a mistake by trying to install osx but to each his own

. I have a fully functional version of OS x on my Hard drive. I recently loaded Vista Ultimate onto my MSI Wind and was hoping for a clean dual boot, but ofcourse nothings that easy. I have Vista up and running now and all is well with that but on boot up it doesn't give me the option to boot up leopard, it just boots straight to vista. I know that my osx partition still has the os on it, untouched, so how can I resolve this (without completely starting from scratch). I looked at my partitions and almost switched my osx partition to active but decided to check with you guys if this would be foolish.
THANX IN ADVANCE!!!!