need help!!!!

ok i just installed my new mobo and updated bios. flashed bios with no problems . when i was done with flashin i cleared cmos and booted pc. test screen comes up and has no problems untill it goes to load os and it beeps 3 times then screen goes blank . award has on 2 beep codes and none of them are 3 beeps. mobo is p2b-l with lastest bios . i even switched vid card to eliminate it as the cause. cpu temps r low . i dunno can anyone help me?????

It would help if we knew what mobo you have, as well as CPU, mem, PSU, vid card etc.

asus p2b-l ,384 pc100 sdram ,300w ps , p3 500 mhz, gef 2 ti 64mb vid