Okay. He's obviously on OFW. Otherwise, why would he specify m33 after 5.00 and not 3.95?
Here. You need a Magic Memory Stick, which can be made extremely easily with the help of some youtube how to videos. You'll also need a Pandora battery. I suggest you look for a Datel battery Tool. Its one of the most useful tools for a PSP.
And yes. If you are going for 5.00 M33-2, go for 5.00 M33-4. Its the latest update.
But please note-If you have the latest PSP-a 3000 series, you can't get a CFW.