I am about your weight, but taller.

I've done two triathlon sprint seasons (seven races / season)

The first year I had the cheapest road bike that I could get - a DBR Interval. It had crappy alloy rims but it did the job.

For the second year, and after catching the bug, I built a new tri-specific bike, and its a monster.

I'm now in the process of building a new road bike - but thats a different story.

My recommendation is to go with a cheap but serviceable road bike (even a flat bar) and then upgrade if you decide you like it.

With regards to wheels - Since I started riding again at the end of 2005, I have yet to break a single spoke, or get a single flat that wasn't a pinch flat. Go with the stock ones, and only get a new wheelset if you find yourself breaking spokes.