One game I love, that's an RPG, and is the only computer game I'll play, is the Guild Wars series.
The graphics, especially on a top spec computer are beautiful! Trust me.
I think the story is great, too, but I'm always told by Wowddicts that the WoW storyline is a tons better... though the graphics aren't worth pot.
The great thing about GW, too, is that it's free online play. Unlike most MMORPGs where you pay £40 for the game, and a tenner each month to play it.