Can't connect to wireless net from Vista even though can see the SSID

I'm setting up a new Vista system, and can't connect to my existing wireless network.  Vista sees the wireless net, with its SSID, but can't connect to it.  The signal strength is at maximum level.  The error message indicates that the "Wireless association failed because Windows did not receive any response from the wireless router."  I have no trouble connecting via a wired Ethernet connection.

The computer running Vista is a new HP Pavilion dv9500.  The wireless network adapter which it uses is a Broadcom 4321AG 802.11 a/b/g/draft-n Wi-Fi adapter.  I've got the latest Broadcom driver installed (version 4.102.15.61).

I can ping the loopback address on the adapter but cannot ping the router itself from the wireless connection (because it's not connected).

I'm currently running with no security (an Open net).  The router is a Westel Versalink W327W combination wired/wireless DSL modem and router.

I have another laptop, running XP, which has no trouble connecting to this same wireless network.

Am I possibly running into trouble with TCP/IP version 6 issues (both V4 and V6 are installed on this connection)?  The wired connection to the same router is also configured with both V4 and V6 and it works fine.

Any help would be greatly appreciated.  Thanks!