I don't think it was a mistake to change the BIOS to boot from CD first. After all, with just windows you might still need to recover by booting from cd. You could also look for a bios upgrade on dell's site.
It's possible to install lilo on the linux partition instead of the MBR and put a line for it in boot.ini, but as the windows bootloader can't boot linux you would still get lilo after NTLDR. If you want to play it safe you can use that or use a bootfloppy for linux.
Putting lilo in the MBR is the easiest method though and if you want to remove it you just boot with a win bootfloppy and issue "fdisk /mbr" or use a wincd and boot into recovery console and issue "fixmbr" and perhaps "fixboot".
I have the same situation with my better half and windows so I've just set lilo to boot as default into windows and told her not to touch the %¤/#! thing until windows has loaded