Was this a fresh install,if so how recent? Is this a dual boot set-up? Did you install all your drivers, motherboard,graphics card,sound,etc?
Boot to your Windows XP disk and select R to access the recovery console. "to repair a windows XP....press R"
Enter the administrator password (blank by default). Type these commands in: COPY X:\i386\NTLDR C\: COPY X:\i386\NTDETECT.COM C:\ where X is the drive letter for your CD drive. Remove the CD and type exit. Reboot your machine and see if that has fixed the problem.
But I see you are having trouble getting far enough with the XP CD to to the above , so your only other option as far as I can see would be to remove the hard-drive,plug it into another PC as a slave,backup your files then reinstall the drive and install a fresh copy of XP SP3.
Others may have suggestions.