Just to help my fellow idiots because it took me at least 6 tries to get the right commands here is an easy to follow xsi to mesh conversion tutorial...
First click Start/Run/and type cmd
a command line prompt window will open and display with this
C:\Documents and Settings\whaterelseitwillsay\blaghblaghblagh>
then change thedirectory path by typing cd
C:\Documents and Settings\whaterelseitwillsay\blaghblaghblagh>cd
followed by the desired path in this case it was
C:\Documents and Settings\whaterelseitwillsay\blaghblaghblagh>cd C:\sinsofasolarempire\ConvertXSI
this is the format to use for converting your xsi file
C:\sinsofasolarempire\ConvertXSI>convertxsi.exe <"nameofyourxsifile".xsi> <"nameyouwantthemeshtohave.mesh> <--nooptimize>
example below...
C:\sinsofasolarempire\ConvertXSI>convertxsi.exe ball.xsi ball.mesh --nooptimize
this will convert the file
in my example the xsi file was moved to this folder for ease of use and i highly recomend it.
ds