Computer won't Boot

I am building a computer from some extra parts I have. The computer will not boot. It is looking for a boot file. Nothing happens when I try to boot
from the 'A' drive with a set of set-up boot disks. I put in my XP disk and
booted the computer. It began to collect some information about the
hardware but it seamed to hang. Before, I partitioned the hard drive into two
with WIN98. This hard drive was in another computer. I took it out and
connected it as a slave to another computer and installed WinXP Home to it
in NTFS. I then took it out thinking it will boot another computer. It
would not boot. So I formatted the drive in my other computer and replaced
it thinking it will install XP from the boot. The computer sees the hard
drive, video card, CD Rom and other boot information but it will not boot.
I have an AMD Duran processor on a ECS Elitegroup K7S5A Pro motherboard with
120MB of memory. I think the memory is SDRAM.

Thank you;
David