My client has an Asus EEE PC model 1005HA, and we're attempting to connect it to the WiFi network created by a VirginMobile MiFi unit.
They also have a MacBook Pro with Snow Leopard that has absolutely no issue connecting to the MiFi.
The specific symptom is that the netbook fails to lease an IP address from the MiFi unit. I supply the 12-digit numerical password (WPA) to the netbook, it throws a 'waiting for network' dialog with an indeterminate progress indicator, and then times out.
Update: We've determined that this behavior has stopped when the EEE PC and the MiFi unit were taken out of the client's home, and to a different home that didn't have an existing wifi network. Similarly, when taken to a third location that didn't have wifi, the EEE PC and MiFi got along swimmingly.
My current theory is that the existing wifi networks and the wifi leg of the MiFi unit are on the same channel and competing with one another. Perhaps the MacBook Pro has the capability to overcome this interference, while the EEE PC doesn't.