As stated, I've just upgraded to 12.04 and my Dell Inspiron 1545 isn't recognising its wireless card and I was wondering if anybody could help?

Edit: Okay, so I found the wireless card by using

lspci -vvv

and it returned this: 0c:00.0 Network controller: Broadcom Corporation BCM4312 802.11b/g LP-PHY (rev 01) Subsystem: Dell Wireless 1397 WLAN Mini-Card Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- SERR- Kernel modules: ssb

lsmod
Module                  Size  Used by
dm_crypt               22528  0 
joydev                 17393  0 
dell_wmi               12601  0 
sparse_keymap          13658  1 dell_wmi
dell_laptop            13671  0 
dcdbas                 14098  1 dell_laptop
psmouse                72919  0 
uvcvideo               67203  0 
serio_raw              13027  0 
videodev               86588  1 uvcvideo
snd_hda_codec_idt      60251  1 
mac_hid                13077  0 
snd_hda_intel          32765  5 
snd_hda_codec         109562  2 snd_hda_codec_idt,snd_hda_intel
snd_hwdep              13276  1 snd_hda_codec
parport_pc             32114  0 
rfcomm                 38139  0 
bnep                   17830  2 
ppdev                  12849  0 
snd_pcm                80845  3 snd_hda_intel,snd_hda_codec
bluetooth             158438  10 rfcomm,bnep
snd_seq_midi           13132  0 
snd_rawmidi            25424  1 snd_seq_midi
snd_seq_midi_event     14475  1 snd_seq_midi
snd_seq                51567  2 snd_seq_midi,snd_seq_midi_event
snd_timer              28931  2 snd_pcm,snd_seq
snd_seq_device         14172  3 snd_seq_midi,snd_rawmidi,snd_seq
binfmt_misc            17292  1 
snd                    62064  18 snd_hda_codec_idt,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm,snd_rawmidi,snd_seq,snd_timer,snd_seq_device
soundcore              14635  1 snd
snd_page_alloc         14108  2 snd_hda_intel,snd_pcm
lp                     17455  0 
parport                40930  3 parport_pc,ppdev,lp
sky2                   53628  0 
ums_realtek            17920  0 
uas                    17699  0 
i915                  414603  3 
wmi                    18744  1 dell_wmi
drm_kms_helper         45466  1 i915
drm                   197692  4 i915,drm_kms_helper
i2c_algo_bit           13199  1 i915
video                  19068  1 i915
usb_storage            39646  1 ums_realtek

ifconfig -a

eth0      Link encap:Ethernet  HWaddr 00:23:ae:24:71:45  
      inet addr:192.168.1.158  Bcast:192.168.1.255  Mask:255.255.255.0
      inet6 addr: fe80::223:aeff:fe24:7145/64 Scope:Link
      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
      RX packets:14340 errors:0 dropped:0 overruns:0 frame:0
      TX packets:10191 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000 
      RX bytes:15403754 (15.4 MB)  TX bytes:1262570 (1.2 MB)
      Interrupt:18 

ham0      Link encap:Ethernet  HWaddr 7a:79:05:2d:b0:f7  
      inet addr:5.45.176.247  Bcast:5.255.255.255  Mask:255.0.0.0
      inet6 addr: fe80::7879:5ff:fe2d:b0f7/64 Scope:Link
      inet6 addr: 2620:9b::52d:b0f7/96 Scope:Global
      UP BROADCAST RUNNING MULTICAST  MTU:1404  Metric:1
      RX packets:0 errors:0 dropped:0 overruns:0 frame:0
      TX packets:179 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:500 
      RX bytes:0 (0.0 B)  TX bytes:27480 (27.4 KB)

lo        Link encap:Local Loopback  
      inet addr:127.0.0.1  Mask:255.0.0.0
      inet6 addr: ::1/128 Scope:Host
      UP LOOPBACK RUNNING  MTU:16436  Metric:1
      RX packets:433 errors:0 dropped:0 overruns:0 frame:0
      TX packets:433 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:0 
      RX bytes:60051 (60.0 KB)  TX bytes:60051 (60.0 KB)

iwconfig

lo        no wireless extensions.

ham0      no wireless extensions.

eth0      no wireless extensions.

the results for sudo lshw -class network

*-network               
   description: Wireless interface
   product: BCM4312 802.11b/g LP-PHY
   vendor: Broadcom Corporation
   physical id: 0
   bus info: pci@0000:0c:00.0
   logical name: eth1
   version: 01
   serial: 00:22:5f:77:1f:e6
   width: 64 bits
   clock: 33MHz
   capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
   configuration: broadcast=yes driver=wl0 driverversion=5.100.82.38 latency=0 multicast=yes wireless=IEEE 802.11bg
   resources: irq:17 memory:f69fc000-f69fffff
*-network
   description: Ethernet interface
   product: 88E8040 PCI-E Fast Ethernet Controller
   vendor: Marvell Technology Group Ltd.
   physical id: 0
   bus info: pci@0000:09:00.0
   logical name: eth0
   version: 13
   serial: 00:23:ae:24:71:45
   size: 100Mbit/s
   capacity: 100Mbit/s
   width: 64 bits
   clock: 33MHz
   capabilities: pm msi pciexpress bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd autonegotiation
   configuration: autonegotiation=on broadcast=yes driver=sky2 driverversion=1.30 duplex=full firmware=N/A ip=192.168.1.158 latency=0 link=yes multicast=yes port=twisted pair speed=100Mbit/s
   resources: irq:45 memory:f68fc000-f68fffff ioport:de00(size=256)
*-network
   description: Ethernet interface
   physical id: 2
   logical name: ham0
   serial: 7a:79:05:2d:b0:f7
   size: 10Mbit/s
   capabilities: ethernet physical
   configuration: autonegotiation=off broadcast=yes driver=tun driverversion=1.6 duplex=full firmware=N/A ip=5.45.176.247 link=yes multicast=yes port=twisted pair speed=10Mbit/s

and the results of rfkill list all

0: brcmwl-0: Wireless LAN
Soft blocked: yes
Hard blocked: yes
1: dell-wifi: Wireless LAN
Soft blocked: yes
Hard blocked: yes