Im looking for the most compact, best performing & easiest flavor of Linux in which INFORMIX-SQL 7.3 is supported. I have looked at PCLinux. The ISQL app is single-user and the end-user is very familiar with DOS, but frightened by Linux.
As long as the Linux kernel and the GNU C library are sufficiently recent, it really doesn't make much difference which distribution of Linux you use. RedHat Enterprise Linux and SuSE are the two officially supported platforms, but most of the other ones will work too.