Replacement Window Options - Atlanta, Georgia

[winatlanta]

We are looking to replace 13 double hung windows in Atlanta, Georgia. So far we have had three quotes:

Champion - Offer their own brand of windows and want $6450 for the job.

Duracraft - Install Gurell windows and said they could install the Gurell 5100 Series windows for $4,875.

Window World - Installs the AllSide 4000 Excalibur for $3,055.

Clearly, Window World has the best price and to be honest, I know nothing about windows and they all seemed about the same overall. However, Window World has a bunch of open issues with BBB down here to the point that they are no longer a member. I do feel that I have some recourse since I could go with them and use a credit card.

Can someone help me compare the three windows that I am looking at? Which one is best, which is worst? I need help comparing apples to apples.

From an installation perspective how hard is it to mess these things up?

Thanks,
J