Having used the package manager to install QGIS 1.6 and GRASS 6.4, an error kept cropping up regarding QGIS being unable to find GRASS. I changed the Gnome 3.x linking libraries to Gnome 2.x and re-started QGIS. I navigated to the parent directory of the GRASS install and clicked OK. Then everything worked fine. I assume it is the Gnome files that caused the problem, but any pointers would be really helpful. Still, it works!
Linking QGIS and GRASS in XFCE