How do I get wifi working on my HP Pavilion dv2000 laptop?

Question

I have seen many questions regarding same issue but not able to get a solution. I'm facing same issue that my wifi is not working in Ubuntu 11.04, but perfectly working fine with Windows 7.

EDIT

sahil@sahil:~$ lspci
00:00.0 Host bridge: Intel Corporation Mobile 945GM/PM/GMS, 943/940GML and 945GT Express Memory Controller Hub (rev 03)
00:02.0 VGA compatible controller: Intel Corporation Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller (rev 03)
00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller (rev 03)
00:1b.0 Audio device: Intel Corporation N10/ICH 7 Family High Definition Audio Controller (rev 02)
00:1c.0 PCI bridge: Intel Corporation N10/ICH 7 Family PCI Express Port 1 (rev 02)
00:1c.2 PCI bridge: Intel Corporation N10/ICH 7 Family PCI Express Port 3 (rev 02)
00:1c.3 PCI bridge: Intel Corporation N10/ICH 7 Family PCI Express Port 4 (rev 02)
00:1d.0 USB Controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #1 (rev 02)
00:1d.1 USB Controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #2 (rev 02)
00:1d.2 USB Controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #3 (rev 02)
00:1d.3 USB Controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #4 (rev 02)
00:1d.7 USB Controller: Intel Corporation N10/ICH 7 Family USB2 EHCI Controller (rev 02)
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev e2)
00:1f.0 ISA bridge: Intel Corporation 82801GBM (ICH7-M) LPC Interface Bridge (rev 02)
00:1f.1 IDE interface: Intel Corporation 82801G (ICH7 Family) IDE Controller (rev 02)
00:1f.2 IDE interface: Intel Corporation 82801GBM/GHM (ICH7 Family) SATA IDE Controller (rev 02)
00:1f.3 SMBus: Intel Corporation N10/ICH 7 Family SMBus Controller (rev 02)
05:00.0 Network controller: Intel Corporation PRO/Wireless 3945ABG [Golan] Network Connection (rev 02)
08:08.0 Ethernet controller: Intel Corporation PRO/100 VE Network Connection (rev 02)
08:09.0 FireWire (IEEE 1394): Ricoh Co Ltd R5C832 IEEE 1394 Controller
08:09.1 SD Host controller: Ricoh Co Ltd R5C822 SD/SDIO/MMC/MS/MSPro Host Adapter (rev 19)
08:09.2 System peripheral: Ricoh Co Ltd R5C592 Memory Stick Bus Host Adapter (rev 0a)
08:09.3 System peripheral: Ricoh Co Ltd xD-Picture Card Controller (rev 05)

sahil@sahil:~$ lsusb
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 002: ID 15d9:0a4c Trust International B.V. 
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 003: ID 0c45:62c0 Microdia Sonix USB 2.0 Camera
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

sahil@sahil:~$ sudo lshw -class network
[sudo] password for sahil: 
  *-network DISABLED     
       description: Wireless interface
       product: PRO/Wireless 3945ABG [Golan] Network Connection
      vendor: Intel Corporation
       physical id: 0
       bus info: pci@0000:05:00.0
       logical name: wlan0
       version: 02
       serial: 00:13:02:c2:ba:22
       width: 32 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
       configuration: broadcast=yes driver=iwl3945 driverversion=2.6.38-11-generic firmware=N/A latency=0 link=no multicast=yes wireless=IEEE 802.11abg
       resources: irq:43 memory:d4000000-d4000fff
  *-network
       description: Ethernet interface
       product: PRO/100 VE Network Connection
       vendor: Intel Corporation
       physical id: 8
       bus info: pci@0000:08:08.0
       logical name: eth0
       version: 02
       serial: 00:16:d3:09:de:80
       size: 100Mbit/s
       capacity: 100Mbit/s
       width: 32 bits
       clock: 33MHz
       capabilities: pm bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=e100 driverversion=3.5.24-k2-NAPI duplex=full firmware=N/A ip=192.168.1.8 latency=66 link=yes maxlatency=56 mingnt=8 multicast=yes port=MII speed=100Mbit/s
       resources: irq:20 memory:d4100000-d4100fff ioport:3000(size=64)

Answer 1

The trace says that your network card is "Disabled".

This happens when either the wireless card has a switch to turn it off - this is either a physical switch or a Fn+ type switch.

If you don't identify the switch then run the following:

rfkill list

This should report all wireless devices as "NO" - i.e. not blocked.

For example for my laptop the results are:

0: acer-wireless: Wireless LAN
    Soft blocked: no
    Hard blocked: no
1: phy0: Wireless LAN
    Soft blocked: no
    Hard blocked: no

If my wireless said "Yes" then I would run:

sudo rfkill unblock acer-wireless; sudo rfkill unblock wifi; sudo rfkill unblock all

Obviously substitute "acer-wireless" for the name of your Wireless LAN as shown in rfkill list