Linux X.Org driver
This chip is not supported by X.org, the best you can get is 640x480 with 16 colors with the 'vga' driver as part of the X.Org distribution
The chip is supported by the "svga"-driver of the older XFree86 version 3 (3.3.6a is found in Debian Woody), though, resulting in 640x480 (or even 640x816 or 1088x480) at 256 colors. For the 750Cs, you additionally need to tweak the video ram by means of Michael Steiner's "tpdualscan.c".
Display on the internal LCD works as long as you set the monitor settings correct.
External VGA port
Linux kernel Framebuffer driver