6.5gb isn't huge, but if you don't click the "install everything" button you'll be fine. also due to the space limitations i'd suggest you stick to a minimal partition layout, as it's hard to move space between partitions if you need to in the future. Are you saying you're going to install Mandriva 2005? if so don't... use somethign modern instead. no point starting of with obsolete software is there?
how long did it take you to put all those Capital Letters At The Start of each Word?