Daily use of the system will be MS Office and web surfing, but it's also going to be used for video editing and music production - and the occasional game I'm sure
I have researched the CPUs and can't see that Turbo Boost is going to make a huge difference for me, so I'd like to understand the difference which the graphics card could make, as £139 is a substational addition for what could result in no distinguishable graphics improvement. I understand that there's also a matter of an additional 1GB of RAM (Windows 7 64bit presumed) but I believe this could be upgraded on the Advent for approx. £35, making a real-term difference between the two machines of £100.
The question therefore is - Should I pay an additional £100 for the Dell with the dedicated 1GB ATI 5450 or should I save my pennies and go for the Advent?
If the added HDMI port the ATI Mobility 5450 will add to your notebook will benifit you then get it but, if you have no need for an HDMI port then the cheaper sienna would be the better option performance wise wont be much different if any the only thing that might take a hit is gaming but, event the 5450 doesn't do well in that aspect of the game either.