You might want to consider LED lamps. While the lamps themselves are more expensive than halogen lamps, they use about 1/6th the amount of power, last many times longer, and current ones are quite bright.

The photo below is one I took comparing a 50 watt Sylvania halogen (left side) to a Philips 10 watt LED lamp (right side). The LED beats the halogen in a number of ways. I must note though that the halogen lamp probably had 1-2k hours on it, so was probably not as bright as a new one. I bought the Philips at Home Depot. At the time, they were rated at 435 lumens. Current ones are rated at 500 lumens, so are even brighter.

If I were looking today, I would also consider the new Cree LM16. But they are a bit pricier than the Philips lamps.

Here is a link that might be useful:

Thank you wws944, after all this time for the advice about getting the LED. I am now looking to replace the halogen MR 16s with LED equivalents. I would love to buy the Cree, but right now they seem to be selling for about $40 each, which seems very high.
I may bite the bullet and get the Cree, though.