There is never too much color!!!!! Lol, I kid…
I got to say I really like what’s already there now with the black/orange. I like in the right column lists with the top fadeout for the rounded corners. Although in the right sidebar ad is sliding out of the bar in FF3.
I’d really recommend you keep it as it is, and just clean up your posts. There’s a bit too much going on there. If you want to change the colors I think it would work, but really it’s a great design as it is.
I realize that you probably want to monetize it or change themes since it looks like you are using a free theme, or just need a change, but I think if you kept the current layout and added in the changes from your mockup (1 featured post, the magazine style blurbs) it would really hit the spot.
BTW – I don’t think there is anything wrong with the new mockup, I just like the current version better ;)