Void your Warranty has put up a Windows 2000/Windows ME dual-boot guide.
First and foremost, backup all your important information! I can't stress this enough. If you don't already own one, a CD-RW drive is money well-spent, and will enable you to keep current information backed up on CD-ROM disks.Read more
Secondly, before you start formatting or partitioning your drive, you'll need to find all of your original Driver disks for all your PC hardware. Here again, having a CD-RW drive comes in handy, as you can download all the updated drivers and have them on one CD, ready to install. If you do download new drivers, make sure you get both the 98/ME AND the 2000 versions. Most of the time, there will be separate drivers for these systems, and in a few cases, there will be specific ME drivers, if you intend to use that OS.