I've performed this hack, and I must say it works perfect for me. Just to be sure, I swapped the 25MHz 040 for a 33MHz and put an active cooler on it. And while I was at it, I also replaced the capacitors.
So if you want to go for a little hack... this one's recommended.
I read that you might get motherboard timing issues. and that a trace on the mb has to be cut?