No, this isn't a post about something everyone should try.... just thought I'd recount my recent PC upgrade experience for anyone that would care to read.
So.......
My main PC was pretty old and tired, although functioning OK (with a minor annoyance of the CD drive having an intermittent recording fault!).  So I thought "let's upgrade"!
Well the choice was relatively easy - I knew more or less how much I was prepared to spend, and what I wanted in return for my money - no "off the shelf" PC gave me the value I wanted, so it was up to me to build my own.
I went for a processor/motherboard bundle (Gigabyte mobo with AMD Athalon 64x2 6000+ CPU, running at 3GHz), a few gig of memory, 512Mb graphics card, and kept my old faithful M-audio sound card.
Fitting the bits in the case was fine, and then I switched it on!
Within about 20 seconds there was a very shrill sound that seemed to be coming from the motherboard - I now know it was the CPU overheat alarm.  Many attempts at getting the thing working ended up with me removing the graphics card, and slowing the processor down to about 1.2 GHz while trying to install Windows - this finally succeeded, but the PC kept getting very hot when under load.
To combat this I replaced the heat-sink and fan, and added an additional case fan.  Things were better, and I got about 2GHz out of the CPU (oh, I also put the graphics card back in).  But still the CPU was overheating when the loading was relatively high (by overheating, I mean on idle it was running at about 40C - under load it jumped easily to 80C, climbing to 100C at which point the PC shut down!)
Clearly this still was no good, so out came the graphics card (slightly better).  That's now been sold to a very happy eBayer!
Finally (yesterday) I did what I expect a few of you would have done long before hand - I bought a new case with a decent air flow (it has one 6" and one 2" extract fan, and one 4" cooling fan).
Having assembled the PC in the case, and made sure everything was working, I cranked the speed up to 2.8GHz (not quite happy to put it all the way yet), and asked my daughter to break it!!!  She managed to get a very hot 65C out of it, but that was after some extreme graphically challenging activities (I think she had 3 simultaneous games running, and was listening to streaming music from Grooveshark).
I have to say, I'm a very happy Jiminuk now.  OK, so it's actually taken 3 months to get this sorted - but it's running fast at nice cool temperatures - and I've learned to not take what appears to be the simplest thing for granted!
That's it!
Jim A

This is an excellent read, not only because it's good to hear from you Jim but because I've also done something similar recently...
.the result...
I've never had a problem with overheating so when you say you change the processor speed.....I wonder how you do that?
This tower of mine has 7 fans 3 of which are directly cooling the radiator for the liquid cooling, it can get breezy under the table lol, but this one hums and occasionally gurgles as compared to my old pc that whines !

Good to hear that you did succeed, I bet you learned loads. 

Hi there Kings - changing the speed that the processor operates at is pretty easy from the BIOS setup, certainly with the Award BIOS that's on the Gigabyte board I have.
It's a question of balancing the Front Side Bus (FSB) and the ratio - so with a FSB of 200 and ratio of 14, I get a throughput of 2800MHz (2.8GHz).  In practice it's not always so exact (I think I get something like 2804MHz!)
Oh, I also dropped the core voltage from 1.42V down to 1.37V.
Gigabyte boards can be tweaked from Windows (the tool is called EasyTune) and I did use that to do some very rough changes while I was looking at how fast I could get the processor working without it starting a fire!  But I don't like to have too many processes running at start-up, so didn't enable this program to run unless I wanted it to (so everything is set from the BIOS).
Your pictures are pretty cool - and you found your water cooled case at the tip!
What did you end up doing with your sound card?

I thought the BIOS would be the place to change these settings, I just haven't had to do it yet.
So do you know the cause of the overheating? That you dealt with it through the bios and windows is one thing, that it was happening is another.
Your processor should be able to deal with a lot of programs running (though I also turn most off) but your graphics card seams on the small side imho, the "old faithful" M-audio could indeed have had something to do with it.
My Creative is 10 years old and still working perfectly....except not in this system! I'll put it back into an XP when I get a new card, I'm now looking at a new M-Audio with MIDI and SPDIF cables.

Yes I found the whole lot at the tip...it was placed in the container with care...so I just picked it up with care and took it home! lol, it's video card was part of the water cooling system but I took it out along with the motherboard and processor, it was an AMD and I've always been an intel / nvidia user.