unsticky sent over a nice snippet of code that helps identify if the user is using IE (of which there are dozens of ways to perform this task) and then, more importantly it can help you identify what is their default browser, if it’s not Internet Explorer using mimeType. A working proof of concept code is here. It works well detecting Firefox and Opera.
There does appear to be at least one false positive when using Netscape. If you are using Netscape in IE mode it will think you are using IE and will still report if that is not your default browser. However, I believe this code would also think your default browser is Firefox if you set it to Netscape since Netscape tends to use the Gecko rendering engine as it’s default (I haven’t tried, but that’s my theory). Anyway, cool snippet of code. Thanks, to unsticky for finding it!