VBA for adding borders to a range based on condition?

I have a spread sheet I use to track tools. One tool may be checked out / returned several times a week. When I do custom sorting I end up with the Tools listed neatly by date and number. EX:

A1 b1
7/11/09 Tool1
7/12/09 Tool 1


7/11/09 Tool3
7/12/09 Tool3 etc.

I have a macro that inserts a blank row between dissimilar tool numbers. What I'd like to add is another macro that adds a box border around the range of cells for each particular tool. So that it looks something like this.

___________________________________________________________

7/11/09 Tool1
7/12/09 Tool 1
___________________________________________________________

___________________________________________________________
7/11/09 Tool3
7/12/09 Tool3 etc.
___________________________________________________________

The problem I'm having is that each time I add a new row to a particular tool number - I have to go in and manually adjust the border. I don't know enough to account for an unspecified range of cells - I never know how many times a tool will be used - or consequently how many cells the box border wit will need to go around.

Any help would be appreciated.