vinyl replacements needed

We are in the beginning stages of getting quotes for new replacement windows. I have started googling and getting ideas and boy
I am now overwhelmed with whats out there. So maybe you can help me narrow down/eliminate to make it a tad easier to decide what might work for us. We currently have wood Marvin windows that are original to the home, about 25 years old... in need of replacing. I have friends that recommended Window World but after checking everything out on line I am not sure about the quality of their install or product. We live in Kentucky and it can get pretty hot here and pretty cold. I would prefer a window that is easy to clean, and will also help with the enery bills. I have ten windows in the front of my brick house that get most of the heat during the day and various types (ie: bay, patio) in the back that will need replacing. Any suggestions??

Going from a Marvin window to a Window World product is probably the equivalent of getting out of an older Ferrari to hop onto a lawnmower.

Don't get overwhelmed. You found a great resource in this board and the pros will gladly help you sort through the minutia and find a good product.

What exactly is wrong with your current Marvin windows?