When you edit lilo.conf and put vga=normal, it will give 640x480 resolution for the text that scrolls by during boot up. If you want higher resolution, you can try the following mode numbers:

Colors 640x480 800x600 1024x768 1280x1024 1600x1200
------------------------------------------------------
256 | 769 771 773 775 796
32,768 | 784 787 790 793 797
65,536 | 785 788 791 794 798
16.8M | 786 789 792 795 799

For example, vga = 788 will give you 800x600 resolution with 65,536 colors. You may have to do trial and error to find one that works. My nforce2 motherboard with integrated graphics also didn't support vga = 791, but I changed it to vga = 788 and all is well. Now I see the pengiun on my screen during boot up!