  Close white dwarf binaries make up a wide variety of objects such as double
white dwarf binaries, which are possible SN Ia progenitors, cataclysmic
variables, super soft sources, or AM CVn stars. The evolution and formation of
close white dwarf binaries crucially depends on the rate at which angular
momentum is extracted from the binary orbit. The two most important sources of
angular momentum loss are the common envelope phase and magnetic braking. Both
processes are so far poorly understood. Observational population studies of
white dwarf/main sequence binaries provide the potential to significantly
progress with this situation and to clearly constrain magnetic braking and the
CE-phase. However, the current population of white dwarf/main sequence binaries
is highly incomplete and heavily biased towards young systems containing hot
white dwarfs. The SDSSII/SEGUE collaboration awarded us with 5 fibers per plate
pair in order to fill this gap and to identify the required unbiased sample of
old white dwarf/main sequence binaries. The success rate of our selection
criteria exceeds 65% and during the first 10 months we have identified 41 new
systems, most of them belonging to the missed old population.
