Metacity gnome-session-flashback seems to give a real desktop performance improvement -- less eyecandy and some of the inconveniences of LINUX of the past. Buttons are on the right> now
I have never had an issue with pci slot netcards and Linux -- only once with an on board network card -- was an ASUS mobo too.
run
$ sudo lshw|more
and find the name of your net card and the model if you are having issues