I 'm having exactly the same problem as you.
In my case the router seems to work fine with my workstation PC that has dual gigabit lan ports and I'm running win 7.
However, my kids computers won't recognize the router at all. One computer is running Vista Home and the other an XP machine. Both of these computers have standard 10/100 Cat 5 eithernet ports.
All three of these computers work fine with the Linksys router that we're replacing.