SCSI miniport driver does not get updatedwhen we do a OS upgrade from Windows 2000 to Windows .NET

hi all,
I have a SCSI miniport driver for windows 2000 and it works on Windows
.NET also. The following is the problem i am running into:

1> I do a fresh installation of windows 2000 on my driver version xx.xx.The
installation completes successfully.
2> I upgrade the OS to Windows .NET and tell the os (By pressing F6) to
install yy.yy version of my driver.But instead it still uses xx.xx version.
3> After the installation is complete i will still see my driver version as
xx.xx.

Can someone put some light on this,
thanks
ajitabh