Leopard MBR related issue

I had a 320 gb windows drive on my dell machine. I shrinked the windows volume and installed iATKOS v5 and it worked fine except i had to fix mbr using windows vista dvd and easybcd. With release of 10.6, i again repartitioned the partition containing windows and reduced by 20gb for Snow Leopard installation. After this i am running into trouble as mac is nt starting. itried to fix it using easybcd but didnt work
i used the mac dvd and again installed boot loader but still its nt working.