|Thank you for the swift reply.|
I downloaded all the appropriate drivers I can get my hands on from Dell's website.
Something which struck me as odd is that earlier today, I ran Windows Update and got 280mb worth of updates.
Upon running my laptop again maybe 3 hours later, the performance had slowed right up, and windows update again found the 280mb of updates - and claimed I had never checked for nor installed them. Some drivers I had downloaded had also magically disappeared.
This is the strangest computing problem I have ever come across by far! I'm thinking either a corrupt hard drive or a corrupt Vista install (it is a few years old and disc is scratched).