Registry

The file c:\system.1st is a copy of the original windows registry made after setup was run for the first time.
At each boot system.dat is renamed system.dao and system.new is renamed system.dat.

To back up registry copy system.dat system.da0 user.dat & user.da0. Windows copys these .dat files to .da0 files on startup.
To back up registry go to Regedit-Registry Menu-Export Registry-Files

Windows setup path= H_L_M_\Software\Microsoft|CurrentVersion\Setup\SourcePath
Add/remove programs = H_L_M\Software\Microsoft\Windows\CurrentVersion\Uninstall
Menu speed = H_C_U\Control panel\Desktop\MenuShowDelay Default 400ms
New Menu = Search registry for ShellNew

MTU & RWIN dial up networking settings

Go to H_K_L\System\CurrentControlSet\Services\Class\NetTrans\ look for DriverDesc=TCP/IP make new string MaxMTU and modify to 576 in same path

New String H_K_L\System\CurrentControlSet\Services\VxD\MSTCP\DefaultRcvWindow="2144"

New String H_K_L\System\CurrentControlSet\Services\VxD\MSTCP\DefaultTTL="64"

Delete all values to return to defaults.