Erm...I'm not quiet sure what your expecting here. Defragmenting your hard drive is a huge task for most computers. Depending on what settings you use (and what program) its either going to take a very long time and allow you to do other tasks with it, or its going to eat up your processing power and not let you do anything. those are really the only easy options.
Now from a technical standpoint the data doesn't HAVE to be on your hard drive in order to defragment it. If you copy your entire hard drive to a different computer/external one then you can run the program on a different computer and save yourself from having to deal with it directly.
Other then that the only other option is to use a different program than the default windows one. Something like tune up utilities 2011. Programs like that are much more efficient than the windows one (although it'll still slow down your computer and take an hour or so depending on how much data you have).