On October 23 2006 I signed a contract with American Vision windows for delivery of 5 windows. the contract said the world would be completed in 4-6 weeks and the sales man offered me one year no interest terms. As it turns out, today May 16th they visited -again- so far they have managed to correctly manufacture and install 4 smaller windows - the main window is still missing, as they simply do not seem to be able to follow the cardboard templates they have made twice after the first window did not fit. To make things worse - they proceeded to charge me for the windows after the first failed attempt to install the windows, interestingly I did not sign for the installation, I did make it clear to them that as soon as the windows were installed I would be happy to sign the paperwork, so instead they asked my girlfriend (whom I am not married to and therefore she can not sign for this) to sign the 'routine paperwork' and they proceeded to charge me based on this signature.
Reviewing the statements from the credit company it turns out that they did not actually give me '1 year no interest no payments' But '1 year deferred interest' - I may not be a financial expert - but this seems to be two quite different things to me. As of today, I have been charged in full, there is no completion date and no offer even for a refund of the work they have no completed.
My recommendation would be to try another company for your windows, and definitely do a internet search before making a agreement, the the internet could have saved me a lot of money.