As a diabetic, I am always concerned about vision issues. Fortunately, my vision is still OK, but it's not what it was 20 years ago. The gradient on the new smooth aluminum windows in Leopard puts button labels in the darkest part of the aluminum. Since the labels are also dark, legibility depends in large part on the shadow and highlights around the label text. This is significantly less legible than most button labels in Tiger, and is going to give folks with reduced visual acuity some problems. Lots of grandparents want Macs too and they don't have the same eyes as 18 year olds. Apple needs to remember that functionality needs to triumph over style in a UI. Reversing the gradient or lightening it somewhat would be an improvement.