Was wondering if anyone on here has any info on replacing windows.  I own a few duplexs and the the windows are in bad shape.  The houses were built in the early 70s and the windows have never been replaced.  I have about 50 windows between the houses that I am looking to replace.  I dont need anything top of the line but also dont want to have to do this again in 10 years.  I had one recommendation of ply gem windows.  Has anyone dealt with this manufacturer?  Most of the windows are roughly 3' x 4'. Whats a decent price for replacing a double hung window of this size including wrapping in aluminum?  Any input would be helpful in my decision.