I just got through playing it on the medium setting. I'll try the highest setting for kicks later, just to see how fast I get slaughtered... But when I do play the game again, it will probably be the challenging setting.
Asus M2N-E, AMD 64 X2 4200, Asus GeForce 9600 GSO, 3GB Kingston DDR2, Seagate IDE 160GB, Maxtor IDE 200GB, Dell 24" E248WFP