[PSP] what's the difference between slim and fat??

Yes, the PSP Slim is lighter! This also means it's more fragile. Personally, I’ve had a PSP Fat for 5 years, and it still works perfectly (a few scratches on the screen, but that’s my fault =p). Meanwhile, all the people I know who bought a PSP Slim have had theirs last less than 3 years. There were issues with the screen (it turns off by itself), with the UMD drive (it reads UMDs only one out of two times) and the Memory Stick reader is the same! So, I recommend buying the very durable PSP Fat or the PSP 3000 (although I don’t have any feedback on that one) but personally, don’t buy the PSP Go either; it’s more cardboard and an attraction for kids than a good PSP!