version 2.0 to 1.5

iv down graded my psp to 1.5 using my 32mb card but do i need the stuff on the 1gb card to play iso games??

If you are asking if you can delete the apps that you placed on your memory card to downgrade your PSP.. then yes.. you can. Just delete the folders you added during the downgrade procedure.

The only stuff you need now on a 1GB memory card is ISOs and of course the UMD Loaders. But meanwhile with just the 32MB card.. you can use some EMU's [Emulators] (Genesis, Nintendo, Super Nintendo, Gameboy and some ROMs) to play at least some cool "old-school" games, plus a few homebrew games as well. When I had just the 32MB card.. I had at lest 32 games!!

But once you want to use PSP ISOs.. then you need at least from 256MB to 2 GB memory cards.

so where do i get the umd loaders?? and do i have to put the isos anywhere??

Well, in the root of your memory stick, make an ISO folder, in all caps, and put your ISOs in there.