Can I play original Xbox games on my 360 if I buy a 20g HD?

I read of forums you need the 250g HD but that seems excessive to play original xbox games.

Is there something special added to the 250g model that allows for backwards compatibility?Can I play original Xbox games on my 360 if I buy a 20g HD?
you basically need a microsoft harddrive that is made for the 360 to be able to play original xbox games. It depends on what xbox version you have. If you have the new slim model 360, the only HDD you can buy that fits into that model is the 250gb...But its also possible to use the old original 360 model hard drive in the new slim 360 if you take off the plastic case to it. I have done this before and my friend has done this for over a year now. If you are using the old original 360 then you just need to buy any HDD that will fit into that system. cheapest is the $20 20gb. And that is the same hard drive you can take the plastic shell off and make it fit into the slim 360 too.