Get a 54G setup, preferably one of the faster 'enhanced' versions, and make sure you get the matching card for the router.
For example, I have the D-Link Extreme G series router, with one laptop card and a wireless brodge (for the PS2, etc). All are from the Extreme G series, which means when you only use them you will get double the normal speed - 108 mbps instead of 54 mbps)- basically I can get my full 10mbps internet connection even when I use the wireless (I download at about 1 MegaByte per second on an good server connection using 128 bit encryption), whereas with a normal 56G connection you only get about 3-4 mbps burst if you're lucky when using high encryption. The downside is that anytime a 'normal' or lower speed connection comes into play, all the connections will drop down and use the lower protocol (for example, I have a networked DVD player that streams audio and video files wirelessly from one of my servers, so if I use it's wireless connection my laptop drops from 108 mbps to 56 - still useable, but drops my download speeds of bigger files down about 60%). Some of the newer technilogy routers will actually have dual internal antennas and will allow mixing of new and old without dropping the speed of the enhanced connection, but expect to pay more for these units.
Use the highest encryption for security (be aware, there is a noticable speed compromise with using the higher encryption settings, which is why I suggest using the 'enhanced' version of whichever company you go for), set up a WEP key (at the very least, WAP is much better) and the best thing to do to prevent people from accessing your physical network is to setup the MAC filters in the router, which will only allow those computers or peripherals whose MAC addresses that you entered into the router to be allowed to connect. You'll have to get the MAC addresses of you desktop, router, and anything else you want to connect (easy enough using the cmd: 'ipconfig/ all' on each machine, or looking for a sticker with the address on it (on the PCMCIA card, router, bottom of the laptop if the wireless is built in, etc.), and anytime a friend comes over you'll have to add his NIC's MAC (I had to do this last night when my friend came by after quitting his job in Manhattan).
It sounds like a lot, but it's not really that hard - once it;s all setup, you'll wonder how the hell you lived without a wireless laptop when you;re sitting outside enjoying a great stick and relaxing
They changes their router and firewall after a while (I could browse every singe file on every computer when they initially set it up - found out by accident when some wierd computer names showed up one day in the Network folder 
)
