OpenGL (Open Graphics Library) is a standard specification defining a cross-language cross-platform API for writing applications that produce 2D and 3D computer graphics.
Basically it competes with Direct3D. Why Google Earth is slow is probably because the driver you were using then couldn't fully take use of your graphics card's abilities.
You should maybe review the configuration file manually and try to uncomment lines talking about fglrx, and making sure that the graphics card driver ("Driver" line) is something else than fglrx -- maybe 'ati' works instead (or 'vesa', it's a generic driver that ought to work, though it won't give you high resolution nor anything fancy - but it ought to give you X anyway).
If you don't have any idea on how to deal with the configuration file, you could post it here. To list it's contents without the commented lines (they aren't needed here, and they just make the file unnecessarily long) you can use grep. To store the xorg.conf contents without comments to a file called 'xorg_conf' under your home directory, run
grep -v "#" /etc/X11/xorg.conf > ~/xorg_conf
You can then read that file (without comments it should not be too long) and post it here if you want.
To modify the file, use either one of these (prefer sudo if it's available):
sudo vim /etc/X11/xorg.conf
If you are not comfortable with the vim text editor, you can use one of the others depending on which ones are available; try substituting 'nano -w' or 'pico -w' instead of 'vim' for easier editing (on those editors: on the bottom you see the keyboard shortcuts; the '^' character means hold ctrl key while pressing the key next to the hat-char).