OpenBSD might work on that laptop, testing it would be the best course of action.
As for the Nvidia graphics, unfortunately.. The only driver available for OpenBSD is xf86-video-
nv(4), this is the 2D driver included with Xorg. (
..the shipped driver may not support your chipset if it's very recent, a failsafe would be xf86-video-vesa(4), but that would not preform well.)
The proprietary driver released by Nvidia for FreeBSD will not work,
compat_freebsd(8) is for userland binaries, not drivers.
Xenocara is the name OpenBSD developers gave to their Xorg port, perhaps you were confusing the
nouveau project, this is a project with the goal of reverse engineering Nvidia graphics cards.. they already know a fair bit about the early chipsets, but no solid 2D/3D driver has come into fruition. (..
and it hasn't been ported to OpenBSD yet.).
The general rule in the OpenBSD community: Avoid
NVIDEA like the plague..