If you are using a framebuffer console, you can add vga=xxx to your grub parameters, where xxx is a 3 digit number from the following table.
Code:
Resolution in pixels
Color depth | 640x480 800x600 1024x768 1280x1024
256 (8bit)| 769 771 773 775
32000 (15bit)| 784 787 790 793
65000 (16bit)| 785 788 791 794
16.7 Mill.(24bit)| 786 789 792 795
An extract form my grub file, as an example, of course you should change the values to match your system:
Code:
title=Linux 2.4.26
root (hd0,0)
kernel /kernel-2.4.26-8 root=/dev/hda3 vga=791 acpi=on