Cannot install Leopard on VAIO

Hi, I have a Vaio VPECEB44EN laptop with an Intel i3 processor and ATi HD graphics.

I've installed Snow_Leopard_10.6.1-10.6.2_SSE2_SSE3_Intel_AMD_by_Hazard that I've burnt on a DVD.

i had to repair win 7 boot and then i added mac boot string through EasyBCD. However, when I try to load it, the computer restarts after displaying the apple logo screen for not more than a second. I dont have any settings in bios other than intel virtualisation and c3/ c6 support. Please help.

Thanks in anticipation
rob