Plug and play is misleading.
1. I assume that P&P is enabled in your bios - you'll know if it is if you have a P&P monitor. 99% of the time it is, but make sure.
2. uninstall all usb drivers previously loaded via add/remove in the control panel. - can be done in safe mode.
3. go to system - either through control panel or via right click on my computer. If there is a yellow question mark highlight it and click the remove device button.
4. reboot PC and have your disk ready.
5. Windows should detect new hardware
6. choose the have disk option when asked. Put the disk into you cd-rom and browse it til you find the folder that says win 9x
7. windows then copies that over to it's database.
8. There may be some back and forth between the CD and your Hardrive. Win 95 and win 98 always gets 'lost' especially if it has to load mulitple drivers (usually Soundcards). you may need to point it to the correct folders using you browse button.
9. cross your fingers!