If you are asking which games, will run on that pc, refer to anort3's post. If you are asking for specific recommendations, it depends on which types of games you like.
If you are interested in mmos or multiplayer shooters I can't really give you much advice. But here are some recommendations.
If you like strategy games, try:
XCOM: Enemy Unknown/Enemy Within
Crusader Kings II
Company of Heroes
If you like games with great stores, try:
Deus Ex: Human Revolution
The Witcher Series
The Mass Effect Series
The Bioshock series
S.T.A.L.K.E.R.
Dishonored