Operating System:
Was installed "FreeDOS" (?) - Replaced by Windows7. Installation without problems.
Missing drivers:
First of finding the driver on the supplied DVD can search. And / or as described herein before, just before looking for (with another computer) the web for "Realtek All-In-One driver". Then you end up on the Realtek page. There you can two (?) Download driver packages. Then the installation of LAN / WLAN drivers will be at hand.
If still more missing driver (see Device Manager):
The program "SlimDrivers" is a freeware, which (in my opinion) the PC well analyzed and then loads the missing drivers and install.