Connected to WEP secured router, but not Internet

[paulpingpong]

Dlink wireless router DI-624:I set WEP encryption at 64 bit with a 10-character password. My laptop (Win XP) has no problem with it. But when I try to use a USB adapter on an older desktop (Win 98SE eMachine Celeron 500), it connects to the router, but not the internet. This same set up has been able to connect to unsecured networks of the neighbors. What config or setting may I be missing?

[GX1_Man]

I always make sure the connection is good in ALL regards before enabling WEP. I would suggest this as a course of action.