Installing Instant Rails over existing Ruby Installation

Rails
1

I just installed Instant Rails on my Windows machine. I previously had
Ruby already installed, and now I seem to have two copies of Ruby, one
in the Instant Rails folder, and my original one in the Ruby folder. My
question:

  1. Is it necessary that I have two separate copies of Ruby?

  2. If not, how do I effectively merge the Gems that I have been using
    with the first copy of Ruby into the copy that is in the Instant Rails
    folders. I would rather have just one copy to maintain and work with.

Thanks,

Alex