Yor main pc new one has to be connected by wires to router and wirelss router then all other computers are either connected to wireless via cable or wirless adaptors.
You need to install wireless router first and setup sharing.
You will need to buy a USB wireless adaptor wich is compatable with ME.The drives you install must be for ME.
Like this one on link?They come in diffrent speeds,the faster speed the more they go up in price.
D-Link United Kingdom
This one supports ME.
WPN111 Support Page
Cheaper option is to buy an internal PCI eithernet card if there is a spare slot inside the PC.No wires just pushes in a free slot,reboot and install drives from floppy disk supplied with PCI card.