Computer Prevents Wireless Connections To Router

I own three computers. One has a wired connection to my wireless router (Linksys WRT54G v. 6 with latest firmware), the other two use wireless adapters and are running Windows XP Professional 32-Bit. If I run Windows 7 Ultimate 64-Bit on the computer with the wired connection, the other two computers cannot connect to the router (access point). Here's what's troubling.

If I leave the other two "wireless" computers turned off, and run Windows 7 on the "wired" computer, then turn off the "wired" computer, and turn on one or both of the "wireless" computers, they still cannot connect.

In order to establish a wireless connection, once again, I must reset the router , then reset the security, and finally, enter the new network key on each of the "wireless" computers. It doesn't matter whether the "wireless" computers are on or off when I either install or run Windows 7 on the "wired" computer. The problem occurs even when I turn off the "wired" computer before turning on the "wireless" computers.

At this point, I can only "assume" (either from lack of knowledge or imagination) Windows 7 actually makes changes to the router's settings. I cannot access the router's web-based utility from Windows 7 or from Windows Vista. I must access it from Windows XP (I quad boot XP, Vista, Windows 7, and Ubuntu). My problem with wireless networking only occurs with Windows 7 Ultimate 64-Bit. I don't experience this problem with Vista Ultimate 64-Bit. Also, I have no networking issues with Windows 7 running on the "wired" computer.

Perhaps there is a simple solution. However, it's disconcerting that Windows 7 can prevent other computers from connecting to my router. Windows 7 should only be concerned with connections made to the computer it is running on, and not take over the responsibility of the router. If this is the case, then I find that to be completely unacceptable. I'm not using the wired computer as a gateway for the other computers. The Linksys router is the default gateway.

Furthermore, I'm absolutely not interested in sharing music or files through Home Group, since this feature of Windows 7 is only compatible with other computers running Windows 7, and I'm not about to replace XP on the "wireless" computers with a beta version of Windows 7. I suspect Home Group might be the culprit here, or the reach of Windows Firewall is now out of bounds.

If you know or have an idea of what might be the problem, please let me know. I'll have to leave Windows 7 alone until I find a solution, as I'm not going to go through the hassle of reseting the router and network keys every time I run Windows 7. Unplugging the computer from the router is an option, but to do so would cripple the OS and the fun of using it. Besides, the beta needs access to the Internet for updates and to report problems.