For those weightlifters in the crowd...

When you lift weights you are burning a ton of calories because is is anerobic.  You need to keep your carb intake up and more protein after your workouts.  The carbs will help you keep on the weight and the protein will help muscles recover and add muscle.  You certainly do not want to bulk up too much if you are a heavy lifter.  Remember to work your core muscles, those are the best muscles to work.  Best of luck in your training.

Mark

Mark's right on the nutrition, and working the core muscles.  You'll use those every time you swim, bike and/or run.  My lifting routine doesn't include any specific work for triceps or biceps; back, chest, shoulders, quads, hamstrings and abs/lower back.  I find that my tris and bis get plenty of work from chest and back sets, and my calves get plenty of work from biking, running, steps and dancing.

Gaining muscle will help you burn more calories when resting (boosts your metabolism quite well), and this will help you loose fat.  You may gain weight, as muscle weighs more than fat.  You must feed your muscles, though - plenty of protein and carbs, and limit fats. 

I'd lighten up the weights some, as you primarily want endurance and not power for triathlons.  Granted, you need strength to hammer up a hill, but you want that strength at the top of the hill, and not just at the bottom.  You may want to compete at 195 in bodybuilding contests, but heavily muscled people typically don't race as well as skinnier endurance-type athletes.