Dell 1370 won't talk to WRT54G

Our aging WRT54G has been used to share a cable modem here for several years without problems. Security is minimal - 128-bit WEP, no authentication as some of the older wireless cards don't support it.

My sister-in-law just bought a Dell laptop which comes with an internal Dell 1370 card. It can be configured using either the XP Wireless Zero or by the Dell WLAN utility; the Dell utility is in control of which utility "owns" the connection. I've tried both.

I tried to set up the 1370 using the same parameters that have worked countless other times. Enter the WEP key as 26 hex characters, be sure authentication is set to "OPEN". The Dell sees the router and that it is encrypted, but it can't connect to it. Signal strength is not an issue.

I've tried entering both the 26 hex and the 5-character ASCII "key generator" versions of the WEP key, into both the Dell Utility and Windows Wireless Zero (not at the same time, actually). It never works.

Worse, the router shuts down the wireless any time an access is attempted using the wrong key, so each and every failed attempt (even rebooting the machine without disabling the WLAN radio) requires a reset of the router. That's how I "know" the Dell is trying to communicate, by the way.

Everything else on the wireless in this house continues to work normally (until, of course, the router gets glitched by the Dell).

Are these just incompatible? Any suggestions?