basic internet connectivity should pretty much work with nothing more than a 10 port hub and a router that can do NAT if not provided by the DSL provider. You can pick up a SoHo router from Linksys or Netgear for well under 100$ with a 4 port switch built in. Add a 8 port hub and you should have room for everything for probably around 150$. Configure DHCP and NAT and you should be good to surf.
This gets everyone connected but if you want to setup a workgroup, map drives, share printers, etc you will probably want to search the archives here, or maybe someone has a good link to offer you. If you get stuck feel free to drop a post here, I am sure someone will be able to point you in the right direction.