Firstly it's nice to see you've added a 'sig' (perhaps you could make it a little smaller? Check this out,
Smaller, (size 1 is good, it takes up less space on the site).
Secondly I found this paragraph very helpful,
By changing the mult or the fsb you get a higher cpu speed. However it is not as simple as just raising both the mult and fsb. First off you need to realize that by raising the FSB you are also affecting every component in your system. The most dangerous thing about overclocking is affecting the harddrive. You want to be careful about the hardrive going above 39mhz because it can get currupted if you do. The default speed of your hardrive, and every other PCI card is 33mhz. Now most of you are probably asking how in the world do i tell how fast the harddrive is running? Well most people who are reading this have either a motherboard based on the via KT266a or KT333 chipset. Both on stock valuses use a 1/4 pci divisor to determine how fast the PCI slots are running. On a stock value of 133mhz, you jus need to divide it by 4 and you will see that it turns out to 33mhz.
(Dear moderator, I hope I'm not overstepping any boundary's quoting a 'sticky', but I think it's for a good cause

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Thirdly, I'm not 'having a go', but I have found that you get better responses to questions if people think you've had a look around to find the answers but, maybe you've just been unlucky and followed the wrong links and got a little lost, and they try to put you back on the right track.
The answers are out there. I'm learning too, as you can see from when I registered, but as far as I'm aware, anything on the IDE ports (eg. CD ROM, hard drive etc.) is controlled by the PCI. Thus if your system 'throws it's hand in' @153mhz fsb, it maybe that your PCI is'nt happy @ 38.25mhz(153/4 (1/4 divisor), but might be happy @ 33.2mhz(166/5 divisor).
Happy hunting.
Jimbo.