This how a virtual company should work :
Put debian stable/testing on all desktops , install virtulabox for things that doesn't yet work in wine , replace exchange with a proper mail server like postfix with proper webmail and users in a database like firebird (also pam can be configured to use it), add samba network shares for document sharing , install a internal local twitter/irc/xmpp channel like status.net
Use google chrome, firefox preinstalled on all desktops , use open source tools instead of msoffice : koffice, openoffice ...
There are so many good tools to choose from take a few examples from osalt http://www.osalt.com/sql-server
Make (php,python,c++) developers to learn Linux and basic command line tasks not to ask the admins every time when they hit the shell on a linux server
These days developers get full root access to the servers at your hand thanks to virtualization
and is imperative that they know howto install a php , a database server like firebird or basic administrative tasks so the best way to make them know Linux/Unix is to put it on their desktops
There is no other way to learn a Operating System than to use yourself daily :I give an example
you want to learn Python then the best way is to use it writing real projects a few months . You can't if you are forced for example to learn .net or other shoddy Microsoft crapware like vb.net or silvernowhere...
Afraid to do migrations ? there are tons of books and migration tools
I know i a few for Microsoft sql to Firebird written in delphi, java , ruby (used at heroku)
On old red book is from IBM , is worth to read it just to give you an example that this is real business not jokes .IBM is the centerpiece of every bank just ask them what they are using for Transaction processing
And they might know a think or two about making money or delivering them ...
You can check the proxy attack from Microsoft towards IBM (bring the popcorn)
another example is NYSE: N.Y.S.E. Places Buy on Linux, Hold on Unix
Think a little bit what developers want this is what they want :better hardware , cars, big salaries , far away holidays ...
There is the money and you give them to ... Microsoft , Oracle , Adobe
Put developers at work and pay them . you would be surprised to find out that the next google is inside your company's open source 20% time projects
Improve the life of the employees they are the gold of company not the buildings, licenses , furniture
I only just noticed these trends , The most successful projects are the opensource ones:
Chrome , Firebird , Linux , Android , MeeGo , QT , HaikuOS , Freebsd , Debian ...
And bean counters found what move the wall street is : freedom to code and change it and the freedom to contribute back to community.The power of money is in love , love of the good craftsmanship and love of work of art : you can't hurry the good wine
Here are some links to read about why is healthy to avoid Microsoft Monopoly
There are many more on techrights.org
If you prefer low quality you prefer Microsoft :How a Preference for Low Quality could lead to Microsoft
Here is how Facebook Scales and does Profit with Open Source
The Corporation has gone Open Source
While Microsoft and friends are doing their best to hide Linux and open-source software from the public, businesses have been adopting Linux and open-source faster than ever. That's not the opinion of FOSS (free and open-source software) fans. That's what Accenture, a global management consulting, technology services and outsourcing company with no particular love for FOSS found in its survey of 300 large private and public organizations.
Accenture "found that half of the respondents (50 percent) are fully committed to open source in their business while almost a third (28 percent) say they are experimenting with open source and keeping an open mind to using it. Furthermore, two-thirds of all respondents (65 percent) noted that they have a fully documented strategic approach for using open source in their business, while another third (32 percent) are developing a strategic plan. Of the organizations using open source, almost nine out of ten (88 percent) will increase their investment in the software in 2010 compared to 2009."