  B-modes of Cosmic Microwave Background (CMB) polarization can be created by a
primordial gravitational wave background. If this background was created by
Inflation, then the amplitude of the polarization signal is proportional the
energy density of the universe during inflation. The primordial signal will be
contaminated by polarized foregrounds including dust and synchrotron emission
within the galaxy. In light of the WMAP polarization maps, we consider the
ability of several hypothetical CMB polarization experiments to separate
primordial CMB B-mode signal from galactic foregrounds. We also study the
optimization of a CMB experiment with a fixed number of detectors in the focal
plane to determine how the detectors should be distributed in different
frequency bands to minimize foreground confusion. We show that the optimal
configuration requires observations in at least 5 channels spread over the
frequency range between 30 GHz and 500 GHz with substantial coverage around 150
GHz. If a low-resolution space experiment using 1000 detectors to reach a noise
level of about 1000 nK$^2$ concentrates on roughly 66% of the sky with the
least foreground contamination the minimum detectable level of the
tensor-to-scalar ratio would be about 0.002 at the 99% confidence level for an
optical depth of 0.1.
