Is that fighting and roleplaying games or games that do a lot of both?
Ys: The Ark of Napishtim is quite good, more of an action RPG and graphics look almost exactly the same as its PS2 counterpart.
Infected's quite good if you're just looking for action: very gorey with lots of blood and guts going everywhere, but can feel a little repetitive after a while.
Tales of Eternia's one of the best RPG's available for the PSP, and you can grab it for quite cheap - i got my copy for £14.99. There's voice acting included so it's not just reading text, great story (so far - i'm not that far in just yet) and has about 60 hours of gameplay.
Let me know if you'd like me to recommend any more.
Oh, and Tekken is a must-buy.
