I am very partial to this window cleaner. It works great and has no amonia in it which is what causes streaking 99% of the time. I always use a paper towel to dry em off and i try to do it in a coller, non-sun lit area so the stuff doesnt dry immediately.
http://www.oznium.com/window-cleaner
This is a very reputable site. I have been ordering from this site since middle of, well, like 2003-2004, put in like 8+ orders and has been great everytime. The site is lighting based, all excellent products, much better then radioshack and most ****ty lighting sites. You need to know what you ar elooking for to try and beat out this site. Never the less, that window cleaner is awesome, i can almost garuntee you wont be disappointed with it.