I'd probably set up an ssh daemon on the windows boxes so the Solaris machine can login and grab the output of srvinfo.exe. You can lock things down so that only specific commands can be executed.

If that's not possible, an alternative is to set up a Windows service that will give you the output of srvinfo.exe when you connect to it. The Windows service could be written in perl. You could even do it with a web server.

There might be some other possibilities using MS remote procedure call technologies.