I have my super heavy beast on a small rolling platform that is only about 2" off the floor. I can easily roll it away to vacuum up cat hair and dust or move it to get at the back. But peasis has a point about working inside it - even if just to blow out dust once a year. I got it many, many years ago at a place that is no longer around.
This is similar to mine... There are ratings for weight load. My computer weighs almost 40 pounds which is still under the 20 pound kg rating. My old computer was even heavier!
Rolling Computer Stand