I have sorted my problem!
The issue that was causing the breakup in sound was the PCI latency settings.
I downloaded a program called powerstrip http://entechtaiwan.net/util/ps.shtm
which allows you to adjust the latency settings of devices such as AGP card, sound card, ethernet card etc.. Seems that the latency was set far too high for my AGP card (248) and also my onboard ethernet (128) which were both hogging the PCI bus while my soundblaster card was set to a latency of 32.
I have changed the settings so my AGP is now 80, ethernet 32 and soundcard 64 and this seems to have done the trick. Will try the best possible combination in due time but it is working very nicely at the moment.
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