AMD Athlon 64 X2 4800+ (2.4ghz dual core)
Nvidia GeForce 9600GT OC
2GB DDR2 ram
If I was not playing the game through Wine, I'd be running Warband at max everything with even this aging setup.
You don't need $1000 to get a very good computer built up. Even assuming that you don't recycle any components and live in California like I do, $639.17 (after taxes and shipping) is enough to leave you set for several years:
http://www.newegg.com/Product/Product.aspx?Item=N82E16811147073
http://www.newegg.com/Product/Product.aspx?Item=N82E16822136847
http://www.newegg.com/Product/Product.aspx?Item=N82E16813157176
http://www.newegg.com/Product/Product.aspx?Item=N82E16814121390
http://www.newegg.com/Product/Product.aspx?Item=N82E16817152035
http://www.newegg.com/Product/Product.aspx?Item=N82E16823664006
http://www.newegg.com/Product/Product.aspx?Item=N82E16820148346
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103808
http://www.newegg.com/Product/Product.aspx?Item=N82E16827151222