A friend of mine visited my site and suggested I turn on http compression. He was even kind enough to provide the code necessary. Everything went smoothly until I discovered IE6 can not handle compressed css files. IE6 only interprets some of a css file that has been compressed. I don't know exactly which parts it chooses to ignore, but background-images are definitely one of them. I was forced to turn off http compression, but luckily only for IE6 and below. Here is the C# code I used to determine if it could handle compression:
bool isIE = false;
if (Request.Browser.Browser == "IE" && decimal.Parse(Request.Browser.Version) < 7)
isIE = true;