Better to replace or repair window? I have a condo beside original installed window that are now 20...

I have a condo beside original installed window that are now 20 years frail. All of the slider windows own condensation between the two glass pane (i.e. seal is broken) and one leak a little from the cup seal when it rain, but otherwise the frame appears fine. Based on the age, would it be worth it (and better) to just replace them instead of have new chalice put in? Would I probably hold other problems later on anyway because of the age? Cost is not an issue. Just want to hear others' opinion. Thanks.
Answers:    I would replace the whole glass. The ones you have presently are probably Aluminum. The new vinyl window do not transmit the cold/heat through the frame like the metal ones do. Plus the window not have a bigger airspace between the pane which is more efficient. You will hold a new warranty that also covers the installation as very well as the product. Replacement glass is an preference but the glass is probably costs approx 80% of the cost of a tentative unit. Go next to the low-e it raises the cost of the pane by 10-15% but it's worth it in the long run. All brands hold to meet a minimum standard so you can but almost any brand and be out of danger. I use Phillips often because they are a virtuous window but credibly priced.
If your window frame is within good condition next replacing the window the thermo pane would be an option. Removing the frame itself is also an leeway and much more expensive.