  Some microquasars are permanently bright radio sources while others are faint
but produce powerful radio outbursts. Most of the X-ray binaries (XRB) however
are very faint or undetected in the radio regime. The European VLBI Network
(EVN) recently introduced the Mark5 recording system which allows data rates of
up to 1 Gbit/s. This increases the sensitivity of the array significantly. We
briefly describe recent developments in the EVN in terms of reliability of the
network and also data quality. We demonstrate the power of the EVN in detecting
sub-mJy radio sources with modest integration times (order of hours). This high
sensitivity capability will permit the study of variable Galactic sources at
milliarcsecond resolution. An estimate is given for the lowest detectable mass
of hypothetical intermediate-mass black holes (IMBH) in nearby galaxies,
provided these are located in radio-jet systems analogous to microquasars and
active galactic nuclei.
