Typing gem on windows:

PS D:\Users\berend.deboer> gem
The term 'gem' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spellin
g of the name, or if a path was included, verify that the path is correct and try again.
At line:1 char:4
+ gem + CategoryInfo : ObjectNotFound: (gem:String) [], CommandNotFoundException
+ FullyQualifiedErrorId : CommandNotFoundException

Same on Ubuntu:

# gem
The program 'gem' can be found in the following packages:
* rubygems1.8
* rubygems1.9.1
Try: apt-get install <selected package>

Really, Windows just feels like an abandoned house, does anyone do any kind of development on this OS? Maybe all using Visual Studio, never leaving it?