Cisco VPN to 3000 Conc..can't surf while connected

I can't figure this one out. I can't get access to the Internet while a VPN
connection is established between a Dell laptop (Inspiron 4100,Win2K)
running the Cisco VPN Client and a Cisco 3000 Concentrator at work while on
my Roadrunner Cable access behind a Linksys router. Now wait a
minute....my Dell desktop (WinXP) running the same client behind the same
router works fine. My Compaq laptop (WinXP) also works fine running the
same client behind the same router. Another anomaly: the suspect Dell
laptop will connect to the Internet while connected through the VPN if I use
a dial-up ISP (of course it is using the modem and not the ethernet card for
this connection). I have this problem on 3 different Dell Inspiron 4100's.
So, I have scoured the settings to look for differences to no avail. Could
it be the network card in the Inspiron, is it the operating system, or have
I missed something in the setup? When I am connected with the Inspiron and
go to a command window, if I ping, there is trouble resolving with DNS. I
can ping the IP addresses though. When I do a Ipconfig /all, it appears the
DNS servers are being assigned via DHCP.
Can anybody help pleeeezzz?