I would like to know about Ubuntu 10.10's new professional themes.
The themes by François Vogelweith that you linked to can be installed by adding a 'PPA'. For instructions on how to do this take a look What are PPAs and how to I use them? - you want to enter
Once you have done this then on the left hand side of the Software Centre click on PPA for Bisigi - from here you can install all the themes.
Once themes are installed you can apply them from System -> Preferences -> Appearance.
Alternative terminal method: (Applications-> Accessories-> Terminal)
sudo add-apt-repository ppa:bisigi/ppa sudo apt-get update
Then go the Software Centre to install the themes as before, and to Appearance to apply them.
I don't know what you mean by "professional," but you can find themes in
If you are using Gnome: http://gnome-look.org/
If you are using KDE : http://kde-look.org/
You can download themes,wallpapers and so on.