Even though I'm at 1080p on my HTPC, I hit this issue occasionally too because I have Medium Sized Fonts enabled in Windows. It is workable for me, but just barely, and I have to move the DSP dialog box around to get to the OK button.
For your immediate problem, though... Many netbooks have a mode where you can put the display into 1024x768 mode "virtually" (where the screen slides around following the pointer). It should be relatively simple to make a few different zones with your preferred DSP settings, while in that mode, and then when the netbook is in its normal native display resolution, you'd just have to switch zones (and not need to open the DSP dialog at all).