Yeah, if it wont come off with strippers or mechanical means then you are out of luck. Even if you did get it off it would never really look like fresh concrete to give you the look you are after. No, sorry to say, i don't think you will have much luck painting it either.
The easiest and cheapest thing to do is just go back to carpet.
To get those really cool looking concrete floors that are polished and have neat colors would be to bust out the floor and start again.
There is a concrete overlay process, i dont have any experience with it. This guy might, give him a call splash
good luck and let us know what you end up doing and post some pics.