Is it even booting past the BIOS screen? Whip the door/s off & check that everything is seated properley.
If this doesn't work try disconnecting the mains supply & removing the CMOS battery on the motherboard (a watch type cell clipped onto the motherboard), then replace it & try booting again. This will reset the BIOS to default values & may solve the problem (ASUS boards can be prone to this).
EDIT:- for hal.dll errors, have a look here;
How To Fix Missing Hal.dll Errors in Windows XP