$osVersion -> Returns the version: Microsoft Windows XP Professional
$osBuild -> Retuns the build: 5.1.2600
$osSP -> Retuns the sp: SP3
$osReg -> Returns the Regname: Norman
(I couldn't find a reliable way to get the $osBits)

Code:
alias osVersion { return $gettok($OSGET(Name),1,124) }
alias osBuild { return $OSGet(Version) }
alias osSP { return SP $+ $OSGet(ServicePackMajorVersion) }
alias osReg { return $OSGet(RegisteredUser) }


alias -l OSGet {
  var %r
  if ($com(osLoc)) { .comclose osLoc }
  if ($com(osSrv)) { .comclose osSrv }
  if ($com(osOS)) { .comclose osOS }


  .comopen osLoc WbemScripting.SWbemLocator
  if ($comerr) { goto error }
  elseif (!$com(osLoc,ConnectServer,3,dispatch* osSrv)) { goto error }
  elseif (!$com(osSrv,ExecQuery,3,bstr*,select $1 from Win32_OperatingSystem,dispatch* osOS)) { goto error }
  %r = $comval(osOS,1,$1)

  :error
  if ($com(osLoc)) { .comclose osLoc }
  if ($com(osSrv)) { .comclose osSrv }
  if ($com(osOS)) { .comclose osOS }
  return %r
}