performance issue!!

[Pramod S]

we have an SUN E450 server with soalris 2.6 and 512mb RAM  running samba. we
have a network and all the machines are connect through a switch. there are
about 40 users who simultaneously use the server running samba for file
service. 
The set up is like this. there is an application on the server which is
shared and all the users have mapped their drive letter to that share. this
application when executed transfers a particular file of about 5 MB size
from the server to the client's machine. 
if only few users are downloading simultaneously then the down load takes
only 2 minutes. but when about 40 users simultaneously try to download the
file it takes about 30minutes. 

can somebody please tell me the factors that could have caused this. 
also can i get information on sizing the server for file services.

any answers for this?????



		PRAMOD.S
		C.S.E
		BENCHMARK GROUP
		WIPROINFOTECH LTD
	   EMAIL -pramods at wipro.co.in
          Ph: (080)5588422      extn- 159