If you had installed Win98 first, when you installed WinNT it would have detected it and offered dual-boot capability. Unfortunately it doesn't work in reverse. At this stage if you want to have both operating systems you could purchase System Commander and have it be your boot manager, then you could not only boot into either o/s, but you could later add others. I've been happily using S.C. for many years and currently have it setup with a menu where I can select Win2000, WinXP, Win98, and DOS (used to also have NT but FAT32 became an issue so I eliminated it).