I haven't actually had much time to play but overall it seems to be OK playback on the preview monitor OK even when resizing. Reading around I found out that Vegas doesn't use the graphics card for processing so it helps.

The only comment additional I would make is that the other laptop I use is running Windows XP and has a 17inch screen, the new DELL is Windows Vista and 15.4 inch widescreen. The 17inch is so much better for editing on Vegas, not sure if it is part to do with the big fonts of Vista which I do not seem to be able to get as small as XP.