Not true, not all of them... mostly they are not, sadly
At least not in mIRC 5.91
Indeed they are.
I was using some script, that completely changed how the mIRC look, but not sure what was the name and where to got it. And more cleaner look (just text, no BS) will be beneficial, too.
You can set mIRC to strip all colours and other codes in Options \ IRC \ Messages
What is the latest mIRC version that run on Win2k anyway?
Look at the downloads page, the link is at the top of this page.