BoxedPixels just to give a few ideas of what to change, most of this has been said but i'll try to explain a bit. . .
The menu on the left, you have white text on the very light buttons, this makes the text quite hard to read you could fix this in a few ways. Obviously the most logical way would be too darken the text, make it a dark grey perhaps? Another way might be to add a shadow to the text tho im not sure that would look too good for this design or you could darken the buttons which might throw off your colour scheme. . .try experimenting see what you can come up with
As mentioned before the header is rather large, you could try making this smaller, try making it so the bottom of the header aligns with the top of the nav, it may look more standard that way but you could try it out to see how it looks, again experimentation is the key
As Tarun said you have a few placement issues, while its not bad how you have it set out it doesn't seem to 'flow' too well. Im not sure on what i could say to you help on this other than to just try and give it some sort of direction, like with everything its just something you have to play around
You have a very nice design and i like the colour scheme alot, but there is just a few minor things you need to fix to make it even better. . . . hope that helps to clear up a few things for you