Looking for a good Single-player PC game

My internet doesn't like to work often, and it decide when it works or not, and as i usually play multiplayer games, but i need a single-player game to play when it (often) doesnt work.

Heres the "rig" (its not much, sue me.)

XP home 

amd athlon 2.4ghz 3400+

1GB RAM

256mb Nvidia 7600GS

plenty of HDD space for stuff.

thanks! (oh and BTW, i have half-life 1&2, so no need 2 mention it)

What genres do you prefer?

Some great games off the top of my head that will run fine are:

Shooters: Far Cry, FEAR, Max Payne 2

RPG/Adventure: Oblivion, Indigo Prophecy, Geneforge Series

Strategy: Rise of Nations, Rome: Total War, Medieval2: Total War, Starcraft, Star Wars: Empire at War

Hope that helps.