Hello all, been a long time. woohoo here we go,

I have volunteered my time to help a friend install and configure a small office network at a summer retreat. the network is this:

5 computers wired on 192.168.10. 10-14 connected to a linksys router (office)
2 computers wired on 192.168.20. 10-11 connected to a linksys router (house)
5 wireless Access Points wired on 192.168.30. 10-14 connected to a linksys router running dhcp for the wireless clients covering the property and lake.
its all in and works, now its time to reach out

There is one internet connection (1.5Mbps with 5 static ip) and I would like to share it 0.5 Mbps to each segment while keeping each separate and secure. it would be nice to allow segments to use idle bandwidth and possibly have the house at 1.0 Mbps and the other 2 at 0.25 Mpbs on demand for skype-voip-confrence.

I have 1 Linux box(Slackware 13) should it have 4 nics or 2 nic with 1 aliasing 3 segments ? how much has changed since ipmasq ? looking for some direction as to kernel compile and howto's that i will need to read. security is important but wanted to keep it as simple as i can.
is Slackware able to dynamically allot bandwidth ? or is cisco the way to go (there is a 2924 and a 2621 on the shelf) leaving the linux box for firewall. but then i'd have to read up on cisco programming too well i could get someone to come in and do the cisco stuff (vlans and shaping) i guess but tell me what you all think.

I have a few weeks to get my head around this so any help would be great.