Here I read that you can even displayy much higher resolutions with VGA than 2048x1536:
http://superuser.com/questions/527192/what-maximal-resolution-is-reasonable-when-using-a-vga-cable

Do we have a good grahpics card supported by MOS that can show resolution like 4k or bigger than 2048x1536? And did anyone test if 2048x1536 looks okay on a PowerMac with G4 or G5 and MOS?