I'm in the same boat as rrfranczak3, as I don't recall the specific details.
Make sure you have the driver installed for your graphics card.
Under windows XP, right click the desktop --> Properties, then on the "settings" tab, click "Advanced".
This next page should have the "Intel" tab.
I'm not on my mini-10 now, but within the "Intel" software, there is a place to change/select your resolution.
The Intel software should allow you to select 1366x768.
I think that's the way I had to do it when I first re-installed windows XP