NTLDR is the file that sits in the root of your C:\ drive and literally loads the system when you power up. You can find a copy in another XP system or in your own files in c:\windows\service pack files\i386 folder. If you take a copy from another system, you can then parachute it into the affected system using a flash drive and a Command Prompt from your XP CD.
Your XP CD is clearly not being recognised when you try to boot from it. Either you aren't changing the BIOS option to boot from CD first, you miss the message about which Function key to press to change the boot order or you miss the message that says "Press any key to boot from CD.
The other files, photos, etc., in the system will not have been affected by this frequent occurrence so if you took the opportunity to upgrade to Windows 7, they could easily be transferred over.