I use to be really big on scratches, liked i'd freak out if i had one.(you can even ask my girlfriend, on how i was)
Ah but the older u get the less u really care about those i guess.
If its on your psp screen, i didn't even know you could get scratches off a screen... i guess it depends on how deep it is.
I dropped my psp as soon as i opened it and it put a mad dent on the side and scratch on the front and i went off my head. Same deal happened with my portable dvd player. I cover the dents up with a little sticker or something.
You should buy a protective screen which woiuld provent scratches i have one on now
So do the right thing: Buy your sister a new one, give the girlfriend yours, and you keep the one with the scratch. Simple, straight forward, and everyone gets to play.
You can use either "Applesauce" or "Brasso" - but make sure to FOLLOW THE DIRECTIONS! If you don't... it will end up worse than before! LOL
BTW - it's not going to be a quick 10 or 20 minute fix. We're talkin' at least a couple hours of polishing to get out all the buffing scratches either in a circular pattern or at very least against the grain of the scratches you're trying to get rid of.