Peachtree 2004 uses Btrieve 6.15 and I have recently added additional
software using Pervasive SQL 2000 client server. I know I can shut
down the Pervasive engine and use Peachtree but is it possible to have
the two running at the same time?

YES, if this is a DOS version using btrv 6.15 for DOS.

Setup a separate environment space for Peachtree to run in. Rt click on
your PIF icon, click the ADVANCED button, and point to a path and file
for a different AUTOEXEC.NT and CONFIG.NT, setup wit hthe params you
need for btrv.
We do the same for DACEasy DOS and Win versions running concurrent.