ASUS A8M2N-LA Problems

Hello everybody here's what I'm working on:

ASUS A8M2N-LA (HP box) (I think this is an Nvidia Mobo)
2.4GhZ CPU
2 GB Ram
500GB Western Digital HDD (Brand New)

I have loaded a fresh copy of XP Pro on this box, It originally had Vista. First things first, when I was creating the partition the system did not recognize the full storage capacity of the HDD (only 131000MB Approx.) Which prompted me to buy a new HDD. I continued with the install and now the system wont get past the Windows XP loading screen. After reading several forums I have attempted to swap around the memory and the HDD to no avail. Any and all help/advise is greatly appreciated. If you need more info on the system please let me know I have listed everything that I believe is pertinent.

Thanks,
DR_Herb