I have a '99 Specialized Allez I've spec'd for Triathlons. I'm upgrading my wheels and have a chance to get a Profile Carbon X Bullhorn aero bar (I'm using Profile clip-ons now) or an aero carbon fork. Both are $150 and I can't afford both.

Given that wheels will add speed what's the better use of $150 to further improve my ride? Fork over for the fork to complement wheels or go for the aero bars?

I appreciate your thoughts!

Approx 90% of aerodynamic drag is caused by the rider and 10% by the bike.

Get aerobars.

I agree totally. For triathlon bike fit / position is everything. You have to be aero, you have to have the steep seat tube angle (cause you get to run after the ride:-)) and you have to be reasonably comfortable in your position which really takes getting used to. Go over to Slowtwitch.com, probably the #1 Triathlon site and join in the fun. P.S. Think about getting a fitting by someone who knows how to set you up. Slowtwitch is a good source for that as well. Good luck!