Awhile back I upgraded to grub2 on my EEE. It looks to be a pretty drastic rewrite from the original, based on all the config files in the boot directory. Anyway, I had the bootup sequence running in 800×600 mode with the original grub because it was a little easier to monitor the screen with the smaller font- the screen doesn’t scroll as quickly. The upgrade to grub2 changed how to configure the terminal mode.
For now, add “set gfxpayload=800×600” to the grub.cfg file in the boot directory. This is the simplest way to do it. Unfortunately, anytime update-grub is run, this setting is lost. Ultimately the config files in /etc/default and /etc/grub.d will need to be modified so the gfxpayload setting will get sucked into grub.cfg when update-grub is run.
Incidentally, the old “vga=788” setting still works but it generates a warning during the boot because its been deprecated. I hate that. Thus I had to go and figure out how to get rid of it with the gfxpayload setting. For those interested, put the vga setting in the /etc/default/grub file as part of the GRUB_CMDLINE_LINUX_DEFAULT.