I have a brand new notebook where I have installed Windows 7 and Ubuntu 12.04 LTS 64bit in dual boot. In windows 7 wifi works but in Ubuntu not.

Could you help me please ?

iwconfig

lo        no wireless extensions.

wlan0     IEEE 802.11bgn  ESSID:off/any  
          Mode:Managed  Access Point: Not-Associated   Tx-Power=20 dBm   
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off

eth0      no wireless extensions.

lshw -C network

  *-network               
       description: Ethernet interface
       product: RTL8111/8168B PCI Express Gigabit Ethernet controller
       vendor: Realtek Semiconductor Co., Ltd.
       physical id: 0
       bus info: pci@0000:01:00.0
       logical name: eth0
       version: 07
       serial: b4:b5:1f:1b:9a:56
       size: 10Mbit/s
       capacity: 1Gbit/s
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=half firmware=rtl8168e-3_0.0.4 03/27/12 latency=0 link=no multicast=yes port=MII speed=10Mbit/s
       resources: irq:41 ioport:3000(size=256) memory:c2404000-c2404fff memory:c2400000-c2403fff
  *-network
       description: Wireless interface
       product: Ralink corp.
       vendor: Ralink corp.
       physical id: 0
       bus info: pci@0000:02:00.0
       logical name: wlan0
       version: 00
       serial: 84:4b:f4:0a:3a:22
       width: 32 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
       configuration: broadcast=yes driver=rt2800pci driverversion=3.2.0-31-generic firmware=0.34 latency=0 link=no multicast=yes wireless=IEEE 802.11bgn
       resources: irq:18 memory:c2500000-c250ffff

lspci | grep -i net

01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 07)
02:00.0 Network controller: Ralink corp. Device 539a

iwlist scan

lo        Interface doesn't support scanning.

wlan0     Interface doesn't support scanning : Device or resource busy

eth0      Interface doesn't support scanning.

lsmod

Module                  Size  Used by
rfcomm                 47604  0 
bnep                   18281  2 
bluetooth             180104  10 rfcomm,bnep
parport_pc             32866  0 
ppdev                  17113  0 
snd_hda_codec_hdmi     32474  1 
snd_hda_codec_realtek   224173  1 
joydev                 17693  0 
hp_wmi                 18092  0 
sparse_keymap          13890  1 hp_wmi
snd_hda_intel          33773  3 
snd_hda_codec         127706  3 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel
snd_hwdep              13668  1 snd_hda_codec
snd_pcm                97188  3 snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec
snd_seq_midi           13324  0 
snd_rawmidi            30748  1 snd_seq_midi
snd_seq_midi_event     14899  1 snd_seq_midi
snd_seq                61896  2 snd_seq_midi,snd_seq_midi_event
snd_timer              29990  2 snd_pcm,snd_seq
snd_seq_device         14540  3 snd_seq_midi,snd_rawmidi,snd_seq
psmouse                97362  0 
snd                    78855  16 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm,snd_rawmidi,snd_seq,snd_timer,snd_seq_device
arc4                   12529  2 
rt2800pci              18715  0 
rt2800lib              58925  1 rt2800pci
crc_ccitt              12667  1 rt2800lib
rt2x00pci              14577  1 rt2800pci
rt2x00lib              51144  3 rt2800pci,rt2800lib,rt2x00pci
mac80211              506816  3 rt2800lib,rt2x00pci,rt2x00lib
soundcore              15091  1 snd
mac_hid                13253  0 
uvcvideo               72627  0 
videodev               98259  1 uvcvideo
v4l2_compat_ioctl32    17128  1 videodev
wmi                    19256  1 hp_wmi
i915                  473240  3 
cfg80211              205544  2 rt2x00lib,mac80211
eeprom_93cx6           12725  1 rt2800pci
drm_kms_helper         46978  1 i915
drm                   242038  4 i915,drm_kms_helper
i2c_algo_bit           13423  1 i915
snd_page_alloc         18529  2 snd_hda_intel,snd_pcm
mei                    41616  0 
serio_raw              13211  0 
video                  19596  1 i915
lp                     17799  0 
parport                46562  3 parport_pc,ppdev,lp
usbhid                 47199  0 
hid                    99559  1 usbhid
r8169                  62099  0

rfkill list:

# rfkill list
0: phy0: Wireless LAN
    Soft blocked: no
    Hard blocked: no
1: hp-wifi: Wireless LAN
    Soft blocked: no
    Hard blocked: no