I’ve been fortunate enough to have dodged the bullet of putting a Dell Latitude 610 on our network recently. However, with the problem you are seeing with the 610, it makes me curious about the Dell Insipiron 9300 that we just added the other day. However, with that laptop, we removed the wireless card entirely and disabled it in BIOS since the user will always use a wired connection to the LAN.
You might be able to do the same thing with the Latitude, although I haven’t fooled around with them too much to know if the card can be removed. If you need to connect to the WLAN, you may have to disable the built in wireless card and purchase a separate PCMCIA card.