On a "proper" dx266 motherboard, the cpu is supplied directly with a
66MHZ signal. (yes I know they called it clock doubling technology,and of
course there is a 33Mhz signal for the "stuff" thats not the cpu).
There is an extra pin in the cpu socket for the faster clock, its on the
inside of the square donut :) , If you don't have one of these, you need an
overdrive, if you do, you can stick an actual dx266 in.
2 very important points :
1) why bother, wait till you can afford a real computer.
2) I'm not comletely sure about anything I may have just said because
I'm too tired to get completely technical, and I'm crapping on from a
vague memory of an article I read a year ago :)