Boot the computer up with a Windows 98 boot disk. At the A:| prompt type FDISK. Once there, say YES to the first screen. On the next screen do a number three follwed by a 4. then do a 3 and 3 then a 3 and 2 then a 3 and 1. (Really dont need all of that, the first 3 and 4 will get ride of the Non_dos partition. Once you have all the partitions deleted. You can re-creat the partition within FDISK by doing a 1 and a 1 to creat your partition. Then reboot and then format and then install.
If this is confusing, re-post and I will try and clarify
Bill