I have a server running Windows Server 2003 that I use as a file server for all my roms and extra files (graphics, videos, etc...) Everything is saved in an "Emulation" folder which I have shared, and I simply map the share on any PC that accesses the server... for example, I map the "Emulation" network share on my main PC as drive E:. I then use E: as the path in all emulator configurations. (i.e. 'E:\ROMS\MAME', 'E:\ROMS\NES', 'E:\SNAPS\MAME'). This way various emulators can be installed on multiple machines and all supporting files are located in one location. Need more storage? Plug another USB external hard drive into the server.
You can have the same setup using a machine running Windows XP that acts as a server, in this case, your laptop. Just create a folder, share it, and you can map it on any computer on the network.
As for connecting... Keep in mind that there are varying speeds when connecting to your network. A basic 802.11b connection will offer you 11mb/second, an 802.11g connection will offer you 54mb/second, and an 802.11n connection will offer you 160mb/second. You have to make sure the wireless adapter you use supports the connection type of your router. If you have an 802.11n router and an 802.11g adapter, you are going to connect with 802.11g and get 54mb/second (wireless routers are always backwards compatible). Some routers offer "Speedboost" or similarly named bursting technologies, but you have to stick with the same brand equipment so if you have an 802.11g linksys router with speedboost you will need a linksys wireless adapter to take advantage of it.
If you have a way to run cat 5e cable to your machines, you can plug the machines into your network and get speeds of 100mb/second. Your router has four LAN ports but supports up to 127 connections so if you run out of ports you can connect a network hub or switch to give you more connections.