Why do my Xbox 360 does this?

Why does it say i need an xbox 360 hard drive to play original xbox games, but i already have a 4g?

• so i bought the Simpson's hit and run for xbox 360. but the game itself is for xbox. it says you need to attach an xbox 360 hard drive to play original xbox games. problem is i already have a 4G one. i think. when i got it in the box it said it was a 4G xbox. has anyone had this problem? and if so, how did you solve it?

• Answer:

  Sad to say, the 4GB xbox does not have a real hard drive, instead it has an internal memory unit, which doesn't count as a hard drive for certain games. The only way to solve it is to buy a hard drive and put it into your xbox. Sorry. When the 4GB xbox first came out, some ads said that it had a 4GB hard drive in it, but now they all say 4GB internal memory unit(or a variation of it).