  This paper presents a ``man on the street'' view of the current status of the
spectral cross calibration between the XMM-Newton EPIC, Chandra ACIS-S3, ASCA
SIS and GIS, and ROSAT PSPC instruments. Using publicly released software for
the extraction of spectra and the production of spectral redistribution
response matrices and effective areas, the spectral fits of data from three
astronomical objects are compared. The three sources are G21.5-0.9 (a heavily
absorbed Galactic SNR with a power law spectrum), 1E0102.2-7219 (a SNR in the
SMC with a line-dominated spectrum), and MS1054.4-0321 (a high redshift cluster
with a thermal spectrum). The agreement between the measured fluxes of the
various instruments is within the 10% range, and is better when just XMM-Newton
and Chandra are compared. Fitted spectral parameters are also in relatively
good agreement although the results are more limited.
