Xessive I know what you mean about it being too toony. Hey pass me some links on the minimal sleek looking stuff. I am too lazy to share mine haha.
Pyro I've never ever had a problem and I've customized my windows to the point where it is unrecognizable -- as Xessive would say -- and it has always run without a glitch.
I recommend you try a program called Microangelo. You can find a torrent and try it out. Messing with icons using that is extremely simple.