Go find a good bike store and talk to the sales guys.
When I say "good bike store", go to one that isn't a mass seller like Walmart, Target or even Trek stores. IMHO, I would stay away from bike shops whose core demographic is families or college kids. If they are predominately selling to families they will most likely not have the depth of knowledge about road biking and competitive racing. If they are selling to college kids (ie store near a university), they know they are selling a cheap bike expensively and the person won't be back in 6 months.
I have found that the smaller, owner/operator type stores are more informed and better at giving you knowledge and service.
When talking to the sales guys, let them do most of the talking and, if you are even remotely intuitive, you will be able to see if they are BS'ing you.
Be honest with them and tell them what you want to do, what your expectations are (road biking now and migrating to triathlons later). They can tailor the bike for you. Also, have them fit the bike for you. By fitting the bike, it should take more than 5 min...it will entail having you sit on the bike and pedal, seeing where you are comfortable and where you feel uncomfortable (stretched too far, too tight, too narrow, seat uncomfortable, etc) and making adjustments to the bike until you are comfortable.
I noticed that you are in Austin.
Lance Armstrong opened a shop called Mellow Johnny's which I would assume would be pretty decent to hire the best in the industry.
You also have Austin Tri-Cyclist, which is a pretty decent tri store and they sell road bike that will let you start with a road bike and then, if you want, to add on additional items to make it more of a tri bike, such as aero bars.
Some decent mass-market brands are Cannondale, Trek, Specialized, Orbea.
At a minimum, you will need:
- HELMET - don't ride without it. Use it on every ride.
- Pedals - Most bikes do not come with pedals and you will need to purchase your own. Get clip-less pedals, such as Look, Shimano or Speedplay.
- Repair kit - Get a bike bag and repair kit, tubes, CO2 cartridges and know how to use it. You will get a flat and you need to learn how to change a tire.
- Water bottle cages and bottles - Couple of cages and bottles
- Shorts/Jersey - Get decent shorts as these will let you sit in the saddle longer and will let you enjoy riding vs. being miserable.
This may seem like a lot and could get expensive, but it need not break the bank.
I did some quick research and found a starter bike package at Austin Tri-Cyclist for $1,000 that will get you everything you need except the clothing.
Good luck. Cycling is great and triathlons are 3x better.