I know exactly what you're talking about, but I have to admit that I've gotten used to the translucent menu bar on my own Mac OS X Leopard (10.5) system. I know, I know, my experience isn't necessarily indicative of how everyone else works with their computer!

Okay, so first off, some great news. If you keep up with the very latest versions of the operating system (easily done by choosing Apple --> Software Update... and ensuring that you're up-to-date) then you'll find that 10.5.2 and beyond have a feature where you can actually disable the translucent menu bar without any hacks or tweaks!

First off, let me show y'all what I'm talking about with a typical translucent menu bar, so you can see how it's a bit tricky to read sometimes:

If you have a solid white background it's probably fine, but lots of people have found that the translucent background for the menubar is more annoying than cool after all.

Now, as I said, in Mac OS X 10.5.2 the "Desktop & Screen Saver" system preference panel has been tweaked. Go to Apple --> System Preferences... and choose Desktop & Screen Saver. Look on the bottom and you'll see:

Uncheck the option "Translucent Menu Bar" and now:

Much better!

Now, perhaps you aren't yet running 10.5.2 and don't want to update? Then I suggest you check out a pretty nifty tip on disabling the translucent menu bar.