Steve- WAY more active and fast. They can run on their hind legs given the space, like a mini T-rex. They are also a sun loving desert species, so their enclosure has far more specific requirements than a nocturnal gecko. I have heard very sad stories about wild caught lizards that die rather than acclimate. I haven't seen that about geckos yet, but it might happen with them too.
David Y- No. No he hasn't. He was really skinny in comparison too. He is getting much thicker now, and he is growing fast. He seems to like being misted sometimes, so I have been trying to get him every other day. The gecko on the other hand, runs for cover. His tail is 10 times the size it started at. He is also growing really fast.
TurboT-I would say that he is more difficult than the gecko, but easier than the turtles. They aren't terribly messy, and the only hard part is getting the temperatures in the cage just right. They need a 100-110 degree basking area, and 85-95 in the warm end. The cool end can be from 75-80. They are amazing little predators, and even at 3 months he could take a full grown cricket. (I tend to be on the nervous side, so he gets 1/2 grown crickets.)Collareds are really fun pets, because they are very active and interactive.
Here's a great site about collareds, done by a lady who really loves the lizards.
http://suncharmers.com/
Posted: Thu Jun 21, 2007 9:41 pm he's getting freindlier..not a turtle, but still cute
He's growing fast! I love the markings. 
