Windows administration support costs ranges from $8000 to $50000 per years as far as i remember. Microsft says it's comparable to linux support costs there :
http://www.microsoft.com/windowsserversystem/facts/analyses/comparable.mspx
And i believe it is... I don't think any of the two system is better than the other in the price area.
Another thing i have to compare is pros and cons of using GPL softwares and other open source licensed softwares.
For me, the main advantage of using a GPL software is that you have the right to modify the software. If you need a specific tool, it will costs far less to take a GPL software that nearly do what you need and add the feature it misses. It'll be cheaper and the tool will be more efficient than if you pay for a big generic software that's not doing exactly what you need anyway.
Another thing: there are many little specialized GPL tools that can be easily gathered together to do a customized application. Sometimes it will only require some clever scripts, sometimes ti will need minor source code modifications.
GPL is good for this because you're sure you can use the source code and modify it freely, with other open source licenses, you don't necessarily have the right to use it in a commercial application or with some conditions.
And i still haven't found any disadvantage.... am i too biased ?
