well, i've just learn how to and did downgrade my 2.71 to 1.50 but now i'm wondering about 3.03 OE C firmware. if i upgrade it to one of these higher or custom firmwares, would i still be able to play with my emulators/roms and stuff? =X thanks.

and another question .. ><' . can someone please explain to me how i can add a wallpaper to the 1.50? for some reason i can't seem to . thanks again.

If you upgrade to 3.03 OE-C, all your homebrew will still work.
All you'll need to do is move it from "ms:\PSP\GAME\" to "ms:\PSP\GAME150\".

oh okay. thanks, i thought so

3.03oec is the most commonly used due to its hacking capabitities, you can do so much with it, but the only thing it is missing is a fourth brightness setting unlike 3.10oea2.
just make sure you have the recovery files incase you want to go back to fw 1.5 if you reconsider.

and another question .. ><' . can someone please explain to me how i can add a wallpaper to the 1.50? for some reason i can't seem to . thanks again.

----> if u upgrade your psp to 3.03oec u can easily change your wallpaper .just go to picture, chose wat picture you want to,hit triangle and chose use as wallpaper....