These days IF I do an overclock on something I tend to just use the built-in overclocks that are often available in the boards.  Im running a 2800+ still, mainly because I cant actually double my performance with an upgrade, and the 3500+ i had fried because it got wet.  Im also limiting myself to 2 PCs and 2 laptops these days.  THough im picking up a VIA C3 Laptop later because the Power port is broken, and the guy who it belongs to has given it to me.  That will probably get used for wardriving and the old P3 will get sold.

On my home machine the only thing Im overclocking is the GF 6600 GT, using trusty Rivatuner. Allows me to run my card at different frequencies and fan speeds simultaneously, like one for 2D (fan low, standard clock), light 3D (fan 90%, tame clock) , heavy 3D (max overclock, max fan speed)...etc.

Wrote a hack/script for Linux also, that runs as a service that achieves the same thing in conjuction with modified Nvclock sourcecode, an excellent console utility.

So wonderfully good dynamic clocking in both windows and linux.

Im running this 64bit s754 Sempron3000 @ 2.25ghz, and it  makes a big difference to performance (iro 8 seconds off a superpi 1M run), and I havent even found its limit yet.

I think the difference is nowadays theres less involved, I remember playing with delta screamers and soldering resistors on to motherboard ...now you just go into the bios and adjust a couple of settings.

Everything I run these days is so badly graphics card (even with my GF7800GTX) limited that I havent overclocked my CPU for years. My trusty Athlon 64 3200+ plods along happily enough.

I have to say that I am considering breaking out the watercooling again in the search for a bit more quiet