Thanks for the tip! Synapse looks pretty awesome. I'll kick gnome-do from the computer. I hope I'll be able to customize Synapse a little, but at least I'm able again to start Google searches without switching to Firefox first.
BTW I found an article with google written shortly after the release of gnome 3 (about it's pros and cons) and the gnome-do-preferences problem is also mentioned there, so I'm not the only one with this problem.
So I'm not worried about gnome-do anymore, but if anyone has other alternative programs, please post any suggestions!
---------- Post added at 08:14 AM ---------- Previous post was at 07:09 AM ----------
I did some googling and found some stuff:
Launchy: Seems to be able to integrate self-defined internet searches (killer feature for me).
Kupfer: Generally looks awesome.
And a list of alternatives to gnome-do.
I'm not under Linux right now, and even if I was, I couldn't try anything out right now (not internet connection --> http://forums.fedoraforum.org/showthread.php?t=265339
ANY help appreciated!!!!!!!!!), but as soon as I tried something out, I'll post it here.