  We present X-ray observations of novae V2491 Cyg and KT Eri about 9 years
post-outburst, of the dwarf nova and post-nova candidate EY Cyg, and of a VY
Scl variable. The first three objects were observed with XMM-Newton, KT Eri
also with the Chandra ACIS-S camera, V794 Aql with the Chandra ACIS-S camera
and High Energy Transmission Gratings. The two recent novae, similar in
outburst amplitude and light curve, appear very different at quiescence.
Assuming half of the gravitational energy is irradiated in X-rays, V2491 Cyg is
accreting at $\dot{m}=1.4\times10^{-9}-10^{-8}M_\odot/yr$, while for KT Eri,
$\dot{m}<2\times10^{-10}M_\odot/yr$. V2491 Cyg shows signatures of a magnetized
WD, specifically of an intermediate polar. A periodicity of ~39 minutes,
detected in outburst, was still measured and is likely due to WD rotation. EY
Cyg is accreting at $\dot{m}\sim1.8\times10^{-11}M_\odot/yr$, one magnitude
lower than KT Eri, consistently with its U Gem outburst behavior and its
quiescent UV flux. The X-rays are modulated with the orbital period, despite
the system's low inclination, probably due to the X-ray flux of the secondary.
A period of ~81 minutes is also detected, suggesting that it may also be an
intermediate polar. V794 Aql had low X-ray luminosity during an optically high
state, about the same level as in a recent optically low state. Thus, we find
no clear correlation between optical and X-ray luminosity: the accretion rate
seems unstable and variable. The very hard X-ray spectrum indicates a massive
WD.
