I finally fixed a little problem that has bothered me for ages. My mouse cursor, which should have been properly alpha blended and multi-colored ended up as ugly 1-bit misshape directly after login, switching themes didn't help and I had for a long time really no idea what was wrong with it and it never was big enough of a problem to really search hard for a solution.
Anyway, with the old broken PC replaced and a new one in place, along with the 1-bit cursor, it was clear that this wasn't a glitch in the graphics driver or Xorg config, but a glitch in my $HOME directory. After a quick replacement of .gnome, .gconf and everything else Gnome related it was clear that Gnome wasn't to blame, which left only one thing, good old .Xdefaults and suprise, suprise, what do we find:
Those entries have been there for ages and as far as I remember where originally created back when Xcursor stuff was brand new and cousing trouble for me. As long as the cursor however was designed for 1-bit that entry wasn't a problem, the problem manifested itself only because Ubuntu's cursor themes are all designed with alpha blending in mind and thus look rather ugly when brute force converted with to 1-bit black&white. With those entries removed the cursor is back to its full color glory and one long running problem finally solved.