apt-get how to block/freeze a certain package version?

Hi,

I am trying to switch to apt-get ( in its rpm version). 

One thing I cannot figure out is how to freeze updating a certain package.
For example I want to have program.1.0.1, but "$apt-get upgrade" will replace it with program.2.0.0, wich is unwanted by me.
I am sure there is a way to do that ....

Also, has anyone tried to update a 6.2 system to 7.x using apt-get???? Just curious.


Kind regards
sasun