Hey CiberTHuG, you said you don't want to use propritary extensions, and I may be totally wrong here , but aren't marginwidth and marginheight MS only extensions? Also just in case you or anyone else doesn't know there is a work around for the fixed positioning thing in IE:

Code:
#menu {
  position:absolute;
}
/*IE doesn't understand html>body, but opera and ns/moz do*/
html>body #menu {
  position:fixed;
}
#menu {
  left:0px;
  top:0px;
  /*ETC ETC*/
}