Question:

Is it possible to run enterprise manager from a nt client and manage a
database that's on solaris?

Answer:

Yes. It is, that's precisely how OEM is designed.  The newer releases
(v2.x) are 3-tier apps, using a console/client, management server, and
repository.  I am currently running the console/client on Win2000, the
management console / repository on NT4, and managing databases on NT4,
AIX, and Solaris.