The Basics of Networking and Wireless Access
1. Make sure you have the same IP scheme (e.g. 192.168.0.x).
2. Make sure you have the same Subnet Mask, Gateway, and DNS IP addresses.
3. Make sure you can ping the other computer's IP address. If this fails, just for testing, make sure you turn off XP's as well as any other firewall.
4. Make sure you can ping the other computers by name.
5. Make sure you have the same workgroup name (watch for trailing spaces)
6. For troubleshooting purposes, turn off XP's and completely uninstall any other firewall software. You can always add more complexity after you get it working.
7. With XP, make sure you have the same username and password as the person logging onto the other computers. The default setting for XP Pro is to require a password for network access.
8. More details about how to network XP can be found at:
http://www.onecomputerguy.com/networking/xp_network.htm
9. More details about how to troubleshoot TCP/IP networks can be found at:
http://www.onecomputerguy.com/networking/trouble.htm
There continues to be a lot of misinformation about needing NetBEUI or to changing the NetBIOS setting. You can ignore both. Installing NetBEUI to solve a networking problem will just mask a some underlying and potentially important misconfiguration with TCP/IP. The default NetBIOS setting usually works. If browsing is a problem, you might set it to Enabled. But do not Disable it.
How to go Wireless
First you need a broadband internet connection (cable or dsl) with a cable or dsl modem that has the capability of connecting by ethernet (cable or dsl modems that can only connect by USB will not work).
Next you will need a wireless router. Wireless routers have 4 ports that will connection of up to 4 computers by wired ethernet. It would be preferable that you connect any computers in the same room as the cable/dsl modem and router by wired ethernet. In that case any computer that is located within easy reach of the router and modem will only need an ethernet network card.
Then, any computer you want to connect by wireless will need a wireless network card. If you are not sure whether or not your computers have wireless network cards, check Device Manger under Network Adapters.
There is really no need to get a wireless router that advertises high speed, unless you are frequently transferring large files between computers on the local network. The standard 802.11g speed routers are much faster than a cable or dsl internet connection, so the higher speed would be wasted with the higher speed routers.
Once your network is setup, you can share any printer connected to any computer on the network, so long as the computer to which it is attached and the printer are powered on.
WPA (Encryption) Setup
Again, instead of rehashing other materail, I'll point you direclty to the sites that have been of help for me. The basic thing to remember is to setup the connection with a hardwired connection first to insure everything is functioning properly with your modem and ISP. next you will want to conifgure the wireless side of the equation without any encryption. Let's get it working without encryption then we can add security in layers. Do not even think about using WEP as your encryption method, becasue it is extremely weak.
WPA is the best for now and use a very strong key (PSK=PreShared Key) as the encrytption password. A minimum of 12 characters including upper and lower case letters with numerals and special characters (%$#@@!&). Gibson Reseach has a 64 bit key generator on his site if you feeel really brave. Just save the key to a text file and copya nd paste as needed.
These are all excellent sites.
http://www.microsoft.com/windowsxp/using/networking/setup/default.mspx
http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=9002706&source=rss_news10
http://www.pcmag.com/article2/0,4149,1277020,00.asp