Originally this game in development was meant to have an open beta from May 12th thru 14th, but they opened it a day early.
http://www.guildwars.com/
You can download the client at the above URL and have a tinker for a few days, if you've never played an MMOG before, or like fiddling with betas then go for it, I assume it still ends on 15th.
Graphics look pretty nice indeed, got it running at 1600x1200 fullscreen with 4xAA.