Ubuntu 12.04 64 bit recognises only 3gb out of 4gb

I have installed it using Wubi from Ubuntu. RAM 4GB. Processor AMD Turion 64 X2 TL-50 dual core. Hard disk 320GB. Basically it is a HP laptop model NX6325. Ubuntu 12.04 64 bit recogises only 3gb out of 4gb. Below is the output of some commands. Let me know if you need any other data

free -m
             total used free shared buffers cached
Mem: 2885 2190 695 0 738 917
-/+ buffers/cache: 534 2351
Swap: 2047 0 2047

lsb_release -a
Distributor ID: Ubuntu
 Description: Ubuntu 12.04.1 LTS
 Release: 12.04
 Codename: precise

uname -a
Linux ubuntu 3.2.0-29-generic #46-Ubuntu SMP Fri Jul 27 17:03:23 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

lshw (for memory)
*-memory
           description: System Memory
           physical id: a
           slot: System board or motherboard
           size: 4GiB
         *-bank:0
              description: SODIMM DDR2 Synchronous 667 MHz (1.5 ns)
              product: JM667QSU-2G
              vendor: 7F4F000000000000
              physical id: 0
              serial: 000974F2
              slot: DIMM #1
              size: 2GiB
              width: 64 bits
              clock: 667MHz (1.5ns)
         *-bank:1
              description: SODIMM DDR2 Synchronous 667 MHz (1.5 ns)
              product: JM667QSU-2G
              vendor: 7F4F000000000000
              physical id: 1
              serial: 000974F2
              slot: DIMM #2
              size: 2GiB
              width: 64 bits
              clock: 667MHz (1.5ns)