Obviosley Your limited by your Computer's resolution capabilitys. Registry tweaking (If thats what you want to call it) is only going to make the problem worse than it allready is.
What you need to do is to get a video upgrade. (A graphics card if you will.) Not too new, just enugh to tide you over for the next 10 or 12 years
If you're not one to buy anything, consider the fact that there are many programs that require an 800 by 600 resolution. and pretty soon, they ALL will. And before you know it, you'll be left in the dust.