Shared_buffers hint

HI people,
I'm tuning a server that is a long time abandoned, and this server is a
little slow.
Now, in my postgresql.conf I have:
shared_buffers = 100Mb
mas_fsm_relations = 15000
mas_fsm_pages = 1600000
max_connections = 300

And I changin' to:
shared_buffers = 1000Mb
(The server has 2 Gb of memory)
mas_fsm_relations = 15000
(The Vacuum noticed me 608 relations)
mas_fsm_pages = 1600000
(The Vacuum noticed me 500800 pages)
max_connections = 300
(I did a "ps axf | grep postgres | wc -l" and the bash brings to me the
number of 120 and all the people is not online at now)

My qustion is about shared_buffers, in postgresql.conf I have: min 128kB or
max_connections*16kB # (change requires restart)
So I did:
300 * (16Kb / 1024) = 4,69?
What this result means?

Thnks all,

Rafael Domiciano