I'm using Vista Premium with WB 5.5.... ATI Radeon x800XT.
For some reason, Gamma Adjustment is NOT WORKING. When I set it in the wb config, I can see the adjusted gamma on the preview like I want it. When I apply the changes, the splash screen as the skin is loading shows the darker gamma. Yet, once the skin is actually applied - there's no gamma adjustment! I have tried this with several different skins and the results are the same on all.
What's up here - why can't I do gamma adjustment!? I have tried it with and without color and HSL enabled/disabled, but that makes no difference. It simply REFUSES to apply gamma adjustment to my windows.
Here's an example (using Optix):

I have applied changes before snipping the screenshot - yet the changes clearly do not take, as you can see that the actual window controls are much lighter in color than the gamma adjusted controls.