I've found linux to be the best environment for doing programming work. The command line is a powerful tool. The key is scripting repetitive tasks, so you only have to ever do them once. Most stuff in windows can't be scripted very easily.

Please expand on the Headline instead of "Ask HN:". Maybe "Ask HN: Use Microsoft products for your startup - Costs Vs Other Factors?"

Consider Microsoft Bizspark http://www.microsoft.com/bizspark/

A program that grants free software licenses for startups. Fairly easy to join.

And once you allow one Business Software Alliance ( http://en.wikipedia.org/wiki/Business_Software_Alliance ) product into your business they claim you have agreed to be audited (which can be expensive even if you are innocent).