Well, its been a few weeks now since I put in a 100GB 7200 RPM drive to replace the 4200RPM 40GB that Toshiba had christened this laptop with. Speed wise, it is noticeable, not as noticeable as I was expecting, but the main points are that I can hit two areas of the disk at once without experiencing the severe performance hit that I was used to on my old disk.
I say, if you are a developer, then shell out the extra for a dual core, but if you are the poor uni student like me (violin music please) then the upgrade has bought a little more life into this lappy till I return to regular full time work.