Hooking up a unmanaged switch to a managed switc...can i still manage?

We currently have 6 hubs that need to be swapped for switches because of problems in our network. There is one head hub, which connects to 5 hubs which then connect to about 12-20 computers each.

We are on a tight budget and i liked what I would be able to do with a managed switch (traffic control, bandwidth monitoring and controlling) but it would be too expensive to replace all hubs with managed switches.

Can I just swap the head hub with a managed switch and all the other hubs for unmanaged switches and still be able to do these things like traffic monitoring and restricting for individual computers connected to the unmanaged switch? Does the managed switch do its managing by the ports on the unit (ie: i would be able to see how much traffic is going through the second port on the managed switch) or by the IP address used (ie: i would be able to see how much traffic is going to a certain IP)?

Thanks a lot.