cater for powershell as well as cmd for windows users

Hi,

I use powershell on windoze, and have updated the script to work with powershell.
My .vimrc settings are:

set shell=c:\windows\system32\WindowsPowerShell\v1.0\powershell.exe
set shellcmdflag=-command
set shellxquote=
set shellquote=\"
(I obtained them here: http://stackoverflow.com/questions/94382/vim-with-powershell)