Your very welcome.
Also you are very lucky to still be at firmware 2.00, should make downgrading super easy.
First upgrade your psp to firmware 2.71
http://dl.qj.net/Firmware-2.71-PSP/pg/1 ... /catid/163
Once you download the file above, plug in your psp via usb and in the root of your memory stick go to
the folder titled PSP. In that folder you should see some other folders, one in particular the GAME folder.
Double click that folder and once you are in the GAME folder make a new folder and title it UPDATE.
Place the file you downloaded in the folder you just created. Unplug the usb cord, then search for the 2.71 Update on your memory stick.
After you are at firmware 2.71 you just follow this tutorial to get to firmware 1.5
http://www.pspbrew.com/forum/viewtopic.php?t=6810
Its quite simple if any further assistance is needed please do not hesitate to ask.