Adobe Acrobat, older ver

Hi;
I would like to own a copy of Adobe Acrobat, but cannot afford or justify spending nearly $300 for the current version (9.0).
If I purchase ver 6, will I be able to read and modify files that were created with a newer version of Acrobat?

Thanks

FW

I have version 6 pro courtesy of the government - you can edit newer files, however there may be some data loss when downgrading. I haven't really run across it yet.

Thank the government for waste - they were throwing it in the dump and I rescued it.