Cooler for a Pentium 4 Lappy to Desktop

Hi all,

I am making my old laptop into a desktop. One of the big reasons I stopped using it many moons ago was it overheated until shutdown.

At the moment I have a stock intel cooler sitting on top of it, which does a very good job but not very secure.
The hole spacing around the 478 socket is 50 X 60mm with 3mm holes.

What I plan to do is use a solid bottom heatsink and drill and tap my own holes where needed. Trouble is I am not sure of what cooler to go for?
There is room around 3 sides of the CPU and a row of caps 20mm from one side.

So I am looking for something that is cheap, available and has a solid base that covers the 50 x 60mm area. so at least 60 x 70mm

Any ideas?

Arctic series may help