Terry,

  Don't know about your other products, but I just upgraded from PH 5.09D
to 7.29C7 (the 7 is a rolling bug fix version, I believe).  Two things we
found in the areas of compatibility.  One is a syntax change.  In 5.09, you
could do DEFINE DF-SOMETHING CHAR*5 = "xxxxx".  Under 7.29, this will
generate an error.  You have to place a space before the asterisk.  This
seems to apply to all datatypes.  It may be documented somewhere, but I
couldn't find it.  This change may also have been introduced in one of the
6.xx versions of Powerhouse that we never upgraded to.  Another problem is
a change in subfile formats between 5.09 and 7.29.  We have some subfiles
that we overwrite or append to on a regular basis.  7.29 (Quiz, at least,
not sure about QTP), will not append to or overwrite these older format
subfiles.  We used QTP to convert the old files to the new format, and
everything worked fine.  These were very minor problems to overcome, and
some of the new functionality made the upgrade well worth doing.

Good luck, Bob Rose