Redirect all except...

Hello!

I have a site (e.g. http:// www.mysite.com/~luigi) I have redirected
to another host (e.g. http://www.anotherhost.com/luigi) using
this .htaccess:

Redirect 301 /~luigi http:// www.anotherhost.com/luigi

It works pretty well, but now I have a problem. The second host
doesn't support PHP and I have some stuff in a sub-directory, that
uses PHP! Gosh!

What I would like to do now, is to redirect all as described above,
except the content of http:// www.mysite.com/~luigi/myphpstuff

Do you have any idea on how to do it?

Thanks.

Luigi