You can run Nautilus or Dolphin in XFCE. The good thing with 11.04 is that
Nautilus is no longer integral to the desktop. Previously if you ran
Nautilus in XFCE you would lose the XFCE desktop and get the GNOME one
unless you ran nautilus --no-desktop from the commandline. Now it is just a
file manager. I prefer Dolphin to Nautilus because it has more features. The
filtering is outstanding and in Nautilus it is very basic. But many GNOME
users find KDE apps overblown. To each his own.