Converting will definitely make it easier for your machine to edit (whether it's a Mac or PC), but something I failed to mentioned is that the converted video will be 2 to 3 times the size of the original. So plan accordingly to help manage disk space and set aside time to render (which will heavily rely on your CPU.)
Most MAC users I know convert to ProRes and then delete the original video files. On the PC side of things that if you decide to delete the original then be aware that you will loose the meta data that is contained in the .htm file.. this contains the aperture, shutter, focal, etc settings. It's not required and more for personal reference than anything.
Check out cineform neoscene (http://www.cineform.com/neoscene/
) for $129. If you shop around you can find it for under $100.