Upgrade : Windows XP Home to Windows XP Pro

1. Copy the root directory and the i386 directory of the Windows XP CD to your harddisk.

2. Extract the Bootsector of your Windows XP CD.

3. Change 2 Bytes in i386\Setupreg.hiv :
a) Open Regedit
b) Highlight HKEY_LOCAL_MACHINE
c) Menu: File -> Load Structure -> i386\Setupreg.hiv
d) Assign an arbitrary name to the imported structure e.g. “Homekey”
e) Goto HKEY_LOCAL_MACHINE\Homekey\ControlSet001\Services\setupdd
f) edit the binary key “default” and change “01” to “00” and “02” to “00”
g) Highlight “Homekey” and select menu: File -> unload structure

4. Burn your new XP Pro CD

5. Install Windows XP as usual.

It sounds pretty simple to do (just some registry changes), but you can’t install Service Pack 2, so you might try to slipstream in the changes to your modified install disc (if that’s even possible).