Where can i download psp games from?

i have a psp 2000 & i want to download games to play on it can i do this without custom firmware? if so how? & if not what is the safest way to get custom firmware? i don't wanna use the battery method so please don't say get the batter. if you could send me a link for the safest way to get custom firmware. its at 6.39 ofw. if i cant put cfw on it yet then can you tell me how to downgrade it so i can. but like i said id like to download the games without custom firmware. please help.