Getting XP to boot again on laptop hdd

I've been piecing together a new laptop from some old parts.

Along the way, a hdd with Windows XP installed on it (yes a legit install) is what I tried to install in this laptop. The problem is that I can't get it to boot.

What happens is that past the laptop's BIOS screen, I get a cursor in the upper left of the screen. Trying to press F8 for a windows boot menu doesn't do anything. In fact NOTHING does anything. I have to turn it off and on.

What I wonder is how best to get this hdd bootable. Ideally, without destroying the current installation (because some software and other information is on the drive that I won't have to reinstall). Also I don't have the XP CD that was used to install XP in the first place.

I know that the drive works because when I booted with my friend's ERD Commander, I was able to view the files on the drive without problem. I tried restoring the system from an earlier install but this, too, didn't work.

How can I restore the boot ability to this drive? Any idea how ERD Commander 2003 could help me do this if I borrwed it again?

 

OK... I managed to snag an XP CD and boot floppies to try a repair install.

I used the floppies to boot, selected "R" for a REPAIR INSTALL, and then it gave me over to the C:\WINDOWS prompt.

This is obviously different than older repair install functions. What am I supposed to do NOW? How do I get it to actually DO the repair?

 

Just for the record, I DID try some of the commands in this "console" which I had to work with. I tried the "FIXMBR" command and the "FIXBOOT" command, if I recall properly. When I tried rebooting, I had the SAME problem - just the cursor. So whatever my problem is, it's not just the MBR.

I imagine I have to do a whole REPAIR INSTALL per se.