the easiest way to set up a dual-boot is definitely with the pull-trays.
"How does the BIOS recognize it?" You set it to "Auto" and it just does. No play, just plug.
The second easiest way (specifically for NT/2K/XP and Linux) is to just use the NT bootloader. Make a boot disk during Linux installation. Install LILO or Grub to the partition superblock - not the MBR! - and then use dd to write that to a file. copy the file to a diskette, reboot into Windows, copy the file to c:\ and add an entry to your boot.ini
The simple HOWTO for doing this. MUCH easier than I just made it sound...I've done this on at least a dozen machines in NT, 2000, and XP, and various versions of Red Hat and *gag* Caldera Linux.