FlyFF Online.

http://flyff.gpotato.com

There might be some problems (For Vista users) but they are minor.
None-the-less just try it out.

Or get Command and Conquer 3. It's buy to play but worth the $$.

Maybe you need this link, below. It shows the list of Vista compatible games.

http://www.thinktechno.com/2007/03/1...patible-games/