Bootmgr = boot manager means the boot sector is damaged..
1. You can repair it with the XP CD... start the CD as if going to install Windows XP but select the first "R" option to open the Recovery Console... then use commands MBR FIX and Enter, then follow with FIXBOOT and hit Enter.... type "exit" to reboot.
2. If you have a floppy drive you can download a bootdisk from bootdisk.com to boot Windows XP then copy the files from the floppy disk to C: ... files are BOOT.INI, NTLDR and NTDETECT. You can also burn the bootdisk on a CD if you don't have a floppy drive, or even on a USB pendrive if your BIOS can boot USB.
3. If you don't have the Windows XP CD, download a Recovery Console ISO to make a Recovery Console bootable CD that loads the Recovery Console and works the same as the WXP CD.
Download this Recovery Console BootCD
http://www.thecomputerparamedic.com/files/rc.iso
To burn the Recovery Console ISO download ImgBurn
www.imgburn.com/
How to use the Windows recovery console
http://www.computerhope.com/issues/ch000627.htm