Yes, I use colored scrollbars. Yes, they're meant for IE only.
You know what they do in Firefox?
Nothing.
You know what they do in Opera?
Nothing.
You know what they do in Netscape?
Liar, no one uses Netscape anymore!
Overall, what do colored scrollbars do in browsers other than IE?
That's right, nothing. Nothing isn't going to hurt you. So get over it. Your computer can handle loading the extra 1KB.
I honestly never understood the huge hubbub people make over colored scrollbars. So it doesn't work in Firefox? You end up with a gray scrollbar? Newsflash: You'd have the same darn gray scrollbar anyway. It adds to loading time? Let's make a webpage with nothing on it but a colored scrollbar and see how much time it takes to load.
If it broke webpages I could understand (for example, i-frames not working in every browser). I've never seen it break a webpage though. Browsers that can't read it just ignore it. The only tangible argument I can see is that it increases loading time; which is a small technicality. The actual increase in loading time would be too minute to matter.
If you were making a business website it wouldn't be very professional to customize a site so personally. But for personal sites? Lay off. Business and personal aren't the same thing. You wouldn't expect every home owner to build a wheelchair ramp just because that's what businesses do, would you?
Heck, this is even less than that. It's more like complaining about the color of the wheelchair ramp, because some people are colorblind.
The site is perfectly accessible. The content is viewable. Why do people hunt for the simplest things to complain about? You wouldn't even know you were missing out on anything if you didn't look at the coding.