I bought the twin 500 watt tripod a couple of months ago, and I found that it made my garage (dimensions: 20 x 20 x 9) unbearably hot. So hot that I had to work with my garage door open. A couple of weeks ago I bought two 8' T5 strips (each holds four four 4' bulbs - combined light output from both fixtures is 40,000 lumens) and mounted those to the ceiling. I now have a TON of light - far more (and far better) light than the halogens put out, and I can now work with my garage door closed. My home is in a new neighborhood and there a cottonwoods nearby, so there's a lot of crap floating in the air. Plus sounds echo throughout the neighborhood, and buffer noise is probably the last thing they want to hear...
The halogens will probably never be used again.
If you do go halogen, put them on a surge protector (I bought a little one plug Belkin surge protector that works great). There are a lot of reports of halogen bulbs exploding (even those cleaned with alcohol). It's my belief that changes in the voltage are one of the causes and the surge protector limits these. At least it did during the limited time I used the halogens - probably a total of 50 hours or so.