[Tristan Lall]

Unless there's something extra about the GDDR3 version, you won't see a big difference in performance by just using faster memory.

The older Dell Inspirons were very good in terms of the availability of graphics card upgrades, but I'm not sure if the 9300 uses a miniature PCI Express interface, or if it's still AGP like the old ones; its 915PM chipset does support it, though. Unfortunately for you, you'll probably have to go through Dell (parts) or eBay--both of which will tend to be expensive for that sort of thing. You might ask Dell if the XPS laptop is parts-compatible with the 9300 (I bet it is--the other XPSs are just colourful versions of other products, well equipped).