No ethernet connection with new instal of 12.04 desktop on Dell Inspiron 1501 laptop - lshw says "network unclaimed"

[Andrew]

I've installed 12.04 (Precise Pangolin) on Dell Inspiron 1501 laptop and
can't get ethernet to work when booting/running from hard disk
installation - however ethernet does work when running from live CD/DVD.
Never had this problem before with previous versions - last one was
10.04 with which both ethernet and wireless network connections worked
fine. I've trawled through various forum postings but to no avail so am
asking ubuntu Users List for help please.

For information, 'lshw -c network' outputs are as follows:

Running from normal/hard disk installation (no ethernet):

*-network               
       description: Network controller
       product: BCM4311 802.11b/g WLAN
       vendor: Broadcom Corporation
       physical id: 0
       bus info: pci at 0000:05:00.0
       version: 01
       width: 32 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list
       configuration: driver=wl latency=0
       resources: irq:18 memory:c0200000-c0203fff
  *-network UNCLAIMED
       description: Ethernet controller
       product: BCM4401-B0 100Base-TX
       vendor: Broadcom Corporation
       physical id: 0
       bus info: pci at 0000:08:00.0
       version: 02
       width: 32 bits
       clock: 33MHz
       capabilities: pm bus_master cap_list
       configuration: latency=64
       resources: memory:c0300000-c0301fff

Running from live CD/DVD (ethernet connection works):

*-network               
       description: Network controller
       product: BCM4311 802.11b/g WLAN
       vendor: Broadcom Corporation
       physical id: 0
       bus info: pci at 0000:05:00.0
       version: 01
       width: 32 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list
       configuration: driver=b43-pci-bridge latency=0
       resources: irq:18 memory:c0200000-c0203fff
  *-network
       description: Ethernet interface
       product: BCM4401-B0 100Base-TX
       vendor: Broadcom Corporation
       physical id: 0
       bus info: pci at 0000:08:00.0
       logical name: eth0
       version: 02
       serial: 00:19:b9:6f:77:bc
       size: 10Mbit/s
       capacity: 100Mbit/s
       width: 32 bits
       clock: 33MHz
       capabilities: pm bus_master cap_list ethernet physical mii 10bt
10bt-fd 100bt 100bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=b44
driverversion=2.0 duplex=half ip=192.168.0.15 latency=64 link=yes
multicast=yes port=twisted pair speed=10Mbit/s
       resources: irq:21 memory:c0300000-c0301f

As I said above I get ethernet OK when running from live CD/DVD, but not
wireless - I can't install the wireless driver. I've come to a bit of a
dead-end with this now so any help will be much appreciated.

Andy