Yes you're correct - it doesn't work on vista due to vista not supporting DOS programs. Due to the format and msipl program both being DOS apps - that's why it will not work.
All the gui does is genetate batch files so those DOS programs can be run without having to manually type stuff into the command prompt, and it also copies the correct files to your memory stick so you can unbrick/upgrade/downgrade your psp.
Here is a rundown of what the gui is actually is doing:
1 - Finds your PSP and stores the drive letter in memory.
2 - Writes a batch file for the programs to format & msipl (to the drive letter you chose in step 1).
3 - Executes the batch files to format & msipl the memory stick.
4 - Asks if you have rebooted the PSP, and asks to confirm that (or during the next step the files will not be writen properly).
5 - Writes and executes a batch file to extract the rar'd files to the memory stick (to the drive letter you chose in step 1).
6 - Gives a prompt of what to run from memory stick, the gui then exits & deletes all the temp pandora/gui files that were extracted to your pc.
As you can see the gui uses the original pandora files to format & make the msipl and then uses a batch file to unrar files to memory stick - all of which are DOS based programs - and as vista does not support DOS that's why it doesn't work.
Summary - You will need to use Windows XP - OR supply me with some programs that logically format a drive and write the msipl which will work in vista - so I can update the gui.
