If you have an extra wireless router, (the old "B" ones are plentyful and cheap!) you can increase your access by connecting it as follows:
In this example, the DLink (on the right) was added. The Linksys is the acting router. (see below)

They need to be set in the same range address:
The Dlink-514, 802.11b wireless router by default was 192.168.0.1
Using Computer 4, I changed it to a static address within the range of the Linksys, “192.168.1.200”, Subnet, “255.255.255.0”
This address should be outside the DHCP assignments used by the Linksys. I have the Linksys using DHCP assignments; 192.168.0.100 ~ 192.168.0.150
I deactivated the DHCP in the Dlink router. You don't want it assigning addresses.
You can use the same SSID for both routers. ( I chose not to. I called one Linksys and the other Dlink) You must use a different channel for both router to avoid collision. Linksys is channel 6, Dlink is channel 11. I live in a remote area, so I didn't use 64 or 128-bit WEP encryption, although you can.
I connected the Linksys to the the Dlink to normal ports (NOT THE WAN). Old routers can require a crossover cable if one router doesn't support MDI/MDIX. Most routers do.
Now the Dlink router is set as an access point and all connections to this access point is routed to the Linksys router which will do the rest. (assign IP)
In your laptops wireless configuration utility, you should see the two access points. You can have windows choose for you. If you would like to keep locked on just one, just turn off WZC.
http://www.ifelix.co.uk/tech/2000.html
I like to be able to turn Wireless Zero Configuration (WZC) on and off, so I've created icons on my laptop.
Wireless networks are becoming more and more common. It's not unusual to be within range of several wireless access points. If your connection stutters, WZC maybe trying to hook you up to another connection. I've found that if WZC is off at start-up, the system may not connect at all. Open Services.msc (click Start/Run type Services.msc). Scroll to the bottom, double-click on Wireless Zero Configuration, and click on the Stop / Start button. Or... you can create shortcuts to do this for you.
Open Windows Explorer and navigate to C:\Windows\System32 (or C:\Winnt\System32 if you're running Windows 2000). Locate the file "net.exe". Right click and hold, and drag it onto the desktop and release. Then choose Create shortcut here. Rename the shortcut to "Stop WZC". Right-click on the shortcut, choose Properties, and click on the Shortcut tab. The Target field will probably show C:\WINDOWS\system32\net.exe. Add a space followed by [color=yellow]stop wzcsvc[/color] (don't forget the space before stop). Repeat these steps and create another shortcut to start the service; just replace stop with start.
Pretty Sweet!