1. The "highlight" is a little excessive. Red links should
do just fine...
2. Internal links should be a different color than "normal"
links, indicating that you'll stay inside the wikipedia.
The "outside" links could be a different color as well (like
it is now), or have the "standard" color to indicate they'll
lead "back to the web".
3. I like the current way that visited links are the same
color as unvisited ones. Please do this by default, or at
least as a user option.