Monitoring heart rate

At work we have a pretty nice little gym: treadmills; ellipticals; spin bike; free weights; weight machines; big TV and area to do yoga or P90X or whatever you want. Most of the cardio machines have a TV or some sort of media attached.
The guy at work who designed the gym (and took suggestions from me!) hosted a training session the other day to go over the AV equipment.
He showed us how to watch TV on the machines and control the channel changing. He also showed us how we can listen to our own music or watch videos from our iPhones or iPods.
The guy who sold my company the equipment came in to show us some tricks on the machines and answer any questions we had. He gave us some great tips, too.
The best one for me was about our heart rate. He told us how to figure it out. Take 220 and subtract your age. That number is your maximum heart rate.
I am almost 37 (so I am using that age for this). My maximum heart rate is 183. I was advised that you should try to maintain your cardio heart rate at 60% to 80% of your maximum heart rate. If I did my math correctly (and I may not have since I was a journalism major) 60% of of my rate is 110 and 80% is 146.
He also told us which ones are the best monitors. He didn’t seem to think one brand was better than another. (And he thought most would work with the machines we have in our gym.) He did say the monitors that strap around your chest are better than the ones that monitor the pulse on your wrist. (Oh, and the monitors on the machines you hold on to aren’t that great either.)
I have a heart rate monitor Curt gave me one year for Christmas. I need to find the strap and start using it again.
(I am traveling tomorrow for a conference and will be back on Wednesday. I hope to post a time or two while away. I also hope to exercise at the hotel gym while I am away.)