Lilo.conf - BT - boot = /dev/sda & root = sda6 ??
Change you lilo.conf to reflect this:
(EDIT: Yes, Thnx PH - I copied and pasted the OP's lilo.conf, only paying attention to the devices being selected)
boot = /dev/sda
timeout = 60
#vga = 769,771/773/792
vga = 769
image = /boot/vmlinuz
root = /dev/sda6
label = BackTrack
other = /dev/sda1
label = Windows XP
table = /dev/sda << edit by pureh@te(forgot that part Re@lity : )
But why didn't you just install Lilo to sda1, in the first place, with the "restore original mbr" un-checked, so it actually gets written there and left.
Then, boot into BT and edit your lilo.conf to add your Windows partition.
Re-boot to multi-boot