Replacement Windows - Alside Ultramaxx vs Milgard Classic

[rkb]

I'm having my home resided and also will be replacing my original windows with new vinyl windows. I have narrowed my choices down to either Milgard Classic that would be installed by a glass company or Alside Ultramaxx that will be installed by the siding contractor. Both windows appear to be the same. The Milgard will cost about $600 more.The Milgard will be air filled and the contractor says the Ultramaxx will have argon, but I have heard that, because the windows have to come over the high altitude the argon is bled out but the contractor says Alside has develeoped a way to keep it in. I live in Colorado, hot in the summer and cold in the winter - not much humidity. Which is a better window ? And should the windows be installed before or after the siding is installed?

[flygirl]

Install the windows before the siding is replaced. Pay close attention as to how the building wrap/vapor barrier/felt intersect with the window flashing. All must work together for success and no leaks.
As for the argon issue - depends where the windows are manufactured and where they end up. If produced at low altitude and are then transported to anything in excess of about 2400ft above manufacture point, the unit could pop.
Watch for a bit of double-speak here - they may be using capillary tubes as opposed to breather tubes - supposedly the capillary tubes are so small as to prevent the gas from escaping.
Wish I could advise on your choices - partial to Milgard, but don't know anything about Ultramaxx. How do the warranties compare? If you have a problem - how close is the factory for repairs?

[ANOTHER WINDOW GUY]

I prefer the Milgard of the two, but if you choose Alside do not choose the Ultra Max but instead the Sheffield. It's the same window with the same price except for the sill design. The UM has very poor water and air test and that was improved substantially with the Sheffield.

[mman]

I agree with flygirl and AWG. I'm partial to the Milgard, and the fact that they are built in Denver should weigh heavily on the decision. Closer manufacturing means better service and quicker response times. Good luck on your purchase.