If you have AutoCad available, you can output it to jpg directly from AutoCad. If not, Visio is an option, as well as one of the many free utilities out there. Some co-workers of mine have used AnyDwg (anydwg.com), but there are many fine tools out there.
I would suggest a search of google for "+convert +dwg +jpg" to gegt a few potential programs. Most offer a trial period to see if you like them. If this is a one time conversion, a trial might be all you need.
Please find nConvert download or go to: http://perso.orange.fr/pierre.g/xnview/enhome.html. This is a free application that handles over 400 different file formats and converts them. I used this to convert the AutoCAD .dwg files to .jpg for my Wireless Control System maps.