^ Hm there are a few versions of the R52 it looks like, the one I am seeing has a Intel 900 with 128MB..
I for now would not run Vista on a labtop, unless it was specificly made for it, has to do with graphics but also with power consumption. Some default settings in Vista are made to have it work smoothly, but reduce battery life.
Aero Glass and all the other frills require memory and CPU power to work.
That said an X300 should be able to run Aero Glass Vista (but the <128MB will probably disable the feature), I have used a PCIxpress X300 for testing without problems.
If you are still using the classic theme, you might only have advantage of the improved security features while running, but thats about it.
Vista (in my view currently) is about security and looks.
Vista is going on my work-desktop next week to see how it behaves during daily work (including program development) together with Office 2007, w'll see, it will need some getting used to with the file-explorer but I like the 'search' box which is actually a combined search/run/connect to network shares without having to click the 'Run...' like in XP.