i personally prefer the taskbar with the rounded edges, it matches the startmenu.
im not sure about if anyone stretches the startmenu anymore, but most people in windows 7 either choose large or small icons, when you choose large, obviously, the taskbar stays full size, when they choose small size, it halves the size. this is where the problems start.... for your taskbar.
with this design, i dont think you can get away with it looking good when it is reduced in size for small icons, but maybe you can? who knows.
also, are you going both task menus or only one? some people have their task bar up the top of the pc.
so far its looking good, and i hope this helps...and dosent hinder you anyway.