Rim choice for fixed wheel TT bike.

It was suggested that Open Pros with fewer spokes may be the way to go, and the article indicated that fewer spokes on a box section rim does not help at all. Aero rims are definitely the way to go for TT speeds, regardless of the weight difference. Maybe this article would answer things a bit more definitively.
http://www.cervelo.com/content.aspx?m=Engineering&i=Aerodynamics

I see although I didn't suggest Open Pros for a TT machine. I suggested clothing choice, positioning and training has much more impact on your TTing and it would be better (and far cheaper) to worry about these aspects before shelling out on expensive aero wheels. BMMF suggested CXP33s which would seem to offer a suitable advantage for little cost difference compared to Open Pros. Since you could leave these built as 32h rather than silly low spoke count, they'd be fine for most riding rather than TT-only wheels.

[FONT=Tahoma][SIZE=2]Paul Merlo's results indicated that the box shaped rim is very inefficient aerodynamically and it is hard to improve the characteristics of this type of wheel by changing the spoking pattern. Using aerodynamic spokes and reducing their number will decrease the drag on this type of wheel slightly, but using a standard aerodynamic rim such as the Campagnolo Omega or the Velocity aero has a greater influence on reducing drag. For instance, a wheel with 32 round spokes in a Campagnolo Omega rim had less drag than a wheel with 16 round spokes in a box shaped rim.[/SIZE][/FONT]