[CentOS] clicking backspace in centos3 makes ^?

While in centos3, using vim and clicking the backspace I see the ^? 
character instead of it actually deleteing the previous character.

In centos4 this was not a problem.

I have rad about remapping keys and such, but can someone tell me what 
the difference between centos4 and centos3 is so I can make the change 
to make it work on centos3.