Well, after posting that everything worked perfectly, everything suddenly went catastrophically wrong. Somehow KDE more or less installed itself. I've no idea why or how. So, I'm going to reinstall .... and am contemplating going back to gnome/xfce.
Problem is, I hate the look of either nautilus/thunar - the toolbars are so heavy, there's no way to change the 'Places/Shortcut pane' (eg, I don't like seeing 'File System/Root' - dolphin lets me hide what I don't want to see, I haven't found another file manager that does that!) ... and generally, I prefer the KDE 4.4 interface. But plasma is driving me mad - it's crashing with a regularity that reminds me of XP pre SP2. That's BAD. So... I was wondering if it was possible to install KDE, but use, say, LXDE/openbox etc - preferably something that doesn't insist on its own file manager, and preferably something that doesn't require editing config files by hand. I can do it, but frankly I don't see why I should need to!
Any ideas? I'm installing gnome for the minute just so that my Vaio is functioning.