After seeing the Ironman movie, I started to have more interest in this high-tech armor character. Apparently there is a separate series in the comics – Ironman War Machine.
The War Machine first appeared in 1979, and was first used by James Rhodes, as Tony Stark had an alcohol problem. It was later used by Stark after a purported death of himself. After that, War Machine has become a spinoff of the Ironman and continued to be a superhero.
What exactly has happened? Stark loses his company to Obadiah Stane and relapses into alcoholism. Rhodes sees this, and he decided to take over the role of Iron Man. He even used it to fight in the Secret Wars. However, he begins to experience headaches while using the armor, and his behaviour has also changed. It is believed that this is happening because the armor was designed for Stark’s brain. The recovering stark hence helps Rhodes maintain the armor. However, Rhodes believes that Start is meant to take over the armor again.
For more information, I suggest you to read this Wiki page http://en.wikipedia.org/wiki/War_machine. If you are really interested, head over to your nearest comic shop and see if you are lucky enough to find the series again. Please let me know if you do 
