I'm likeing the colour theme but unsure about the diagonal pattern on the gradients (.tcat & .thead) as when you scroll it gives off that icky feeling. The same kind of feeling when people use scanlines on backgrounds and you get that awfull feel when you scroll. I would personally remove the diagonal pattern.
The logo looks mediocre. Nothing great but not bad, Maybe scale the text to a higher setting to give it a more prominant look?
The tcat collapse markers would look better scaled down with a bevel added for perspective. I would also opt for a white marker against the blue gradient instead of the yellow.
Again, with the collapse marker (this time the thead collapse) scale it down and add some kind of bevel and possibly go with a white marker, maybe.
I noticed you've still go a vast majority of default vb images which I think you should replace for some custom images (starting with replacing the images on the index page).
I would work on the style (more importantly) the graphics that compliment them to get a better feel and more consistent look. Love the colour, I just don't like the patterns you intergrated on the gradients.
Goodluck with your site.