I bought one of these and it works very well. It cleans large windows fast without streaking. It vacuums the water so the usual mess from a regular squeegee is not there. If the windows are real dirty I pressure wash them first.
Amazon.com: Karcher WV 50 Window Vacuum Cleaning Power Squeegee Equipment Tool
http://3184402.r.msn.com/?ld=d3oHryQ...p%3d1335010026