advanced bandwidth limiting

[Matej Puntar]

Hello

I have a LAN with 5 computers and a FreeBSD 5.2.1 server that is also 
the gateway.
I would like to limit the upload and download bandwidth.

But I would like to limit the bandwidth depending on how many users is 
surfing
at the moment.

If only one user is surfing or downloading he would have all the bandwidth.
If 3 users are surfing every one would have 1/3 of upload and download 
bandwidth.

Is this posible with FreeBSD 5.2.1 and how?

Thanks