I'm wondering if a 8mb video card support 1440x900? If not, what is the minimum video card to support 1440x900?
width * height * 4 = ...
4 because we want 32bit color, 32bit = 4bytes
In your case: 1440 * 900 * 4 = 5 184 000 ~ 5MB ;)
The problem might be with an old card, that the (old) driver doesn't support this, unless you're lucky, and the manufacturer has even today still driver support for such an old graphics card.