I am afraid you are stuck with 800 X 600. That is the physical limit of the display. (number of pixels) You could try replacing the LCD with a higher res one, but I don't know if the rest of the hardware would support higher res... ( I doubt it)

BTW I am running 10.3.9 on my old clamshell 366 with no problems. Not as fast as my G5 iMac running 10.4, but hey it works fine!
Macbook 2.1 core duo 1gig 160gb sata
iMac g5 w/1 gig 160gig all-in-one and SWEET!
iBook G4 IGhz
Quicksilver Dual 800's
iPod touch
"Guys, I think we just lost the platform here" Pete Conrad
When in doubt, try SCE to AUX