Need help - major computer startup problem

Hey - I am new here and am seeking immediate help. I just built a computer with an EPOX mobo (AMD A64 3400+ CPU) and had just finished installing the mobo drivers. (I was prompted to install SP4 for Windowz XP before continuing - no idea why? maybe because it needed SP1 and i had 2 isntalled?) I went ahead with the install and restarted. When it became to the black DOS startup screen (before the windowx logon) it said the file NFTS.nif (may not be exact) was corrupt or missing and that i needed to put the WIn XP CD back in and hit r to repair it. So I put in the CD and restarted.

Now all it does is fly through the system specs part (right at startup) and go straight to a black screen with a blinking cursor in the top left. I can't do anything either. Keyboard (tried USB and PS2) doesn't work when I try to enter BIOS/Startup Sequence. All I ever get anymore is a startup from the specs to the screen witht eh cursor. Right before this happened - I entered BIOS and enabled USB support for Keyboards and Mice and changed startup from 1) HDD to 2) CD Rom to 1) CD Rom to 2) HDD. Any help would be greatly appreciated (sorry if this post is in wrong forum).

Harris