w98undo.dat

The w98undo.dat file is a file created when you upgrade to Windows 98 from an older Microsoft OS. It is all the data that your previous OS used (or something like that. Yeah.) and when you uninstall W98 it uses this to restore thing to the way things were before.

Sure you can delete it, but you won't be able to uninstall W98 unless you use format c: /s. Keep that in mind when nuking stuff.

The w98undo.dat file is, as it is the only way out, the most important file on your system. Deleting it is just like closing a door from the inside that only can be opened from the outside - you will regret it.

What is that you say? One can install Linux without uninstalling W98? Oh, then, delete it.