I'd suggest getting your feet wet with 3.5e DnD. Minor changes from 3.0e but enough that starting there makes more financial sense. You'll understand better whats going on with 4e if you start there and be able to decide which system you like for yourself. As opposed to simply starting with 4e and never knowing if you would have enjoyed 3.5 and all of the campaign material that has built up over the years with it. The rule conversion from 3.5 to 4e isn't very complicated so don't worry about a drawn out learning curve if you do decide to switch over at some point. You'll be able to pick it up quickly enough if you understand 3.5e.
Hope this helps and may your rope never break,
Onamii
