While owning a bonafide road bike certainly isn't a triathlon prerequisite – plenty of entrants trudge along on hybrids or mountain bikes – becoming a regular road rider is part of the appeal of the triathlon. There's also no question a road bike is better suited for the job, and when you're going for a short, fast 12 to 25 miles (the difference between a sprint and standard course), aerodynamics make a huge difference.
Those $300 funny-looking helmets may shed some time (often at the cost of a little embarrassment), but the gear that will make the biggest dent in cutting out the wind resistance is a set of aerobars. Look for clip-on bars, like the Bontrager Race Lite Clip-On aerobars that we used, so that they aren't just adding weight for casual weekend rides. Be sure to give them a long test ride if you can – there are a number of different shapes and sizes and they take some getting used to. [$120; bontrager.com]