Sun's own site shows it as compatible with the OS.
Here's the E450 resource page in the Sun System Handbook:
http://sunsolve.sun.com/handbook_pub/Systems/E450/E450.html
It shows the system as functional on every release since Solaris 2.5.1 HW 11/97
(which was the 2.5.1 release needed for systems with a PCI bus)