I haad a similar problem with a desktop and Dell 1408 Monitor, 1440 x
900 px.

My initial install, 7.04 I believe would not configure to 16x10.

Have since up-graded to 8.10 and now 16x10 in native resolution is on
the menu.

Perhaps worth buying more ram, if you can easily add more, and going
for a more recent distribution.