When ordering soundproof windows look for Rw value. Standard Rw value is 28dB, but you can also order 32, 36, 40 and even 44dB ones. I got 44dB ones, and even though I live in a city centre, the noise was reduced dramaticly - form 38dB (very noisy) to 24dB (almost dead quiet).
By recomendation of a company that designed my dedicated listening room, I went with the aluminum frames instead of wood/plastic ones. They are more expensive, but do not loose their soundproofing as easyly as the other two (thwy may deform over time). Also importand is the number of seals that the frames have - usually they have just one, but you can order (as I did) up to three.
I'm sorry that I cannot recommend any specific company, since I live (and ordered) in Europe.
By recomendation of a company that designed my dedicated listening room, I went with the aluminum frames instead of wood/plastic ones. They are more expensive, but do not loose their soundproofing as easyly as the other two (thwy may deform over time). Also importand is the number of seals that the frames have - usually they have just one, but you can order (as I did) up to three.
I'm sorry that I cannot recommend any specific company, since I live (and ordered) in Europe.