I keep getting this error "Error Initializing 640 x 480 Mode" whenever i try to start.. installed fine on a windows xp 3.06 ghz 512 meg of ram system with plenty of hard drive space... can't figure out whats going on anyone else seen this error?

I have seen that on the non GOG version. Solved it by putting a check mark in every box in the compatibility menu for the Fallout executable and setting it to Win95 compatibility.
I don't know if that will help with the GOG version...

no i don't see any of those options when i try to run the GOG version its just a double click on a icon and screen goes black and beeps at me and gives me that error... very odd

you should still be able to find the executable file itself and poke around in its Compatibility menu..
should be named Fallout.exe

I did a quick googling around and it seems that this problem only occurs on ATI video cards, do you have ATI? If so, try installing the latest Catalyst drivers.
If that doesn't fix the problem, then you could also try High Resolution Patch

To my knowledge, there is no high resolution patch for Fallout 1. And we don't know which Fallout the OP is referring to...

You have the right click on the shortcut or the exe itself and click properties at the bottom. From there click the compatibility tab and do what JudasIscariot said.

try some of the methods used in the FAQ

I could be wrong...I just never remembered there ever being a high-res mod for the first Fallout, just the second one...I guess I better learn to read the stickies more often :D