Update: Check out this follow-up question: Gem Update on Windows - is it broken?
On Windows, when I do this:
gem install sqlit
I had the same problem on Windows and I have installe MinGW http://sourceforge.net/projects/mingw/files/Automated%20MinGW%20Installer/MinGW%205.1.6/MinGW-5.1.6.exe/download and the problem has gone :-)
C:>gem install hpricot Successfully installed hpricot-0.8.2-x86-mswin32 1 gem installed Installing ri documentation for hpricot-0.8.2-x86-mswin32... Installing RDoc documentation for hpricot-0.8.2-x86-mswin32...
C:>gem install ruby-postgres Successfully installed ruby-postgres-0.7.1.2006.04.06-x86-mswin32 1 gem installed Installing ri documentation for ruby-postgres-0.7.1.2006.04.06-x86-mswin32... Installing RDoc documentation for ruby-postgres-0.7.1.2006.04.06-x86-mswin32...