First, install Windows 2000 and leave some space on either another partition or another drive.
Proceed to install Linux, but don't install the boot loader to the MBR. Instead, install it to the first partition of your linux installation. If possible, make a boot disk during the installation. If that's not possible, then most distros allow you to boot into linux in "rescue" mode. This ussually entails booting from the CD and mounting your system as RO.
We must pull the Linux boot loader information off of the hard disk and copy it to the Windows system so that the NT loader can boot us into Linux.
# dd if=/dev/dev1 of=/tmp/linux.bin bs=512 count=1
Now we need to get this file to Windows. Either copy it to floppy, or over FTP/SSH/whatever.
From Windows, put a record of this file into your "BOOT.INI" file like:
C:\linux.bin="Linux"