Since Red Dead redemption will never see PC, there is a pretty good alternative.
Call of Juarez. Just D/Led it off steam the other day and its pretty good.
http://www.youtube.com/results?searc...of+juarez&aq=f
edit: There's acutally two Call of Jaurez games titles. It's the 2nd one is subtitled "Bound in blood" and is a prequal and improves over the first title. So if you had to get one of them, get bound in blood.
edit: I love the gritty and rawness of this game. lol