First bit of advice I would give you is to have several window replacement companies come out, look at the job, show you their preferred windows, and bid the job. DO check their references, ins, etc.
Regarding which window and options to select, I can't tell you, but do your homework, which ever windows you chose, it will be an investment in your home, and you will have them for a long time.
That being said, I never like to provide a window without LowE2 and Argon gas, for the slight increase in initial cost, you will get a much better performing unit over the life of the window. You can try www.ppg.com for info. on glass, they are a leading glass company with good info on glass options.
As far as Silverline goes, they would not make my top five list of windows I would put into my house.
I prefer vinyl for replacement windows, no maintenance, and a much better value for the money. If you are thinking of vinyl, look at the UltraMaxx from Alside (www.alside.com), or Great Lakes Window. I like Alside, but both make a good product.