Could I get a quick reffernce to your PC? There now alot of games for less than 20$ that look great!
But for now some of these can work on nearly any system...
-Recetear/Chantelise - A Vendor-Sim? its suprising fun and addictive, with a tad of randomized dungeons. I've played Recetear alot more than Chantelise though.
-Sequence - Rythem Based, i'd recommend a controller over keyboard/mouse while playing it though, Funny Dialog/story, and the gameplay can get challanging too.
-Star Wars:Knights Of The Old Republic - MY GOD, i've replayed this game about 12-14 times and I still love it to this day, I only wish they had the sequal.
-Fable (original) - This is now on steam and I was pretty happy about replaying it. Other than some gameplay machinics, Its my favorite of the series.
-Half-Life Original/BlueShift/Opposing Force - fun ol' Half-Life, I can't wait for the next delay of Half-Life3!!!