Your options David are a hub, router, wifi access point, bluetooth, or peer to peer cable. You're not building a big company network so like Pcghost said stay away from routers/switches. A hub or better yet wifi/bluetooth is scalable if u want to add more pc's/laptops later but otherwise why add clutter? You can hook them up directly. Put a NIC card in each machine and run a net cable right between them, the newer ones dont need a central hub. I assume it's a piece of cake to then configure in Mandriva. Just post back in the Linux-Networking forum for help.
These days thanks to the chinese you can even find an affordable USB-to-USB networking cable without a need for opening up the pcs (they have micro-NICs between them) but you need to test their compatibility with ur distro.