  The Galactic microquasars GRS1915+105 and GRO J1655-40 were targets for
dedicated monitoring programs with RXTE throughout 1996 and 1997. We review
recent results with particular attention to the X-ray QPOs seen in these
sources. We confirm the reappearance of 67 Hz oscillations in GRS1915+105 in
several different spectral states. Six intervals, each of 1 to 6 months
duration, yield QPO detections with a central frequency of 66.7 +- 1.4 Hz and a
FWHM of 3.4 +- 1.0 Hz. Comparing these observing intervals, the average X-ray
luminosity varies by a factor of 4 with no significant change in the central
QPO frequency. GRS1915+105 has been active in X-rays since 1992, and it shows
no signs of evolving toward quiescence. In contrast, GRO J1655-40, which began
its most recent X-ray outburst on 1996 April 25, is seen to fade below 20 mCrab
on 1997 Aug 17. There are no reappearances of the 300 Hz QPO during the entire
second half of the X-ray outburst; during this time the X-ray spectrum is
dominated by the soft, thermal component. There are still several models
seeking to explain the high frequency QPOs in microquasars. While it is likely
that the cause invokes some effect of General Relativity, the correct model and
the details of the emission mechanism remain uncertain.
