bootcfg /rebuild looks for windows installations and puts them in your boot.ini I think. You can type bootcfg /? for info about the different commands.
fixboot fixes the partition boot table of the selected XP installation (if you have multiple XP's you have to select XP (1), XP (2), etc).
fixmbr fixes the boot record of the active primary partition.
Maybe this site is more helpful: http://support.microsoft.com/kb/314058
TheMajorMMX - Intel P200 MMX @ 225Mhz - V-Tech (PcPartner) Baby-AT mb w/ Intel Triton TX chipset - Nvidia Riva TNT2 M64 w/ 16MB - 256MB M-Tec SDRAM - Still running.....