Is there a way to identify the network activity for running processes ? I'm seeing some unusual activity on my computer (late 2008 MacBook Pro )
Yes, quite a few - ranging from the simple to the more complex. Depends on what you're after in terms of detail, but if you want a nice, easy GUI frontend (that ties up process names with activity) then you could use something like Little Snitch or Hands Off!. They are actually firewalls, which have their own network monitors. So if you find something you don't like, you can always block it.
Or for something more detailed you could investigate the terminal