The Linux Gnome style that I like is Shiki-color + Gnome colors icon theme. It looks pretty and professional and it is fast.
How to install them:
# yum install gtk-murrine-engine
# yum install gnome-colors-icon-theme
Dowload from here: http://gnome-look.org/content/show.php/Shiki-Colors?content=86717
Install it by Appearance Preference -> Install.
Appearance Preference -> Customize:
Window Border: Shiki-Colors-Metacity