More RAM not recognized -

[Bob Goodwin]

    This Dell DM4700 came with 2-256 mb strips, some time ago I added
    2-1 gb strips for a total of 2.5 gb.

    This morning I replaced the 256 mb strips with 2-2 gb for a total of
    6. The bios setup screen shows 6 gb but apparently Linux is only
    using half that amount, not much of an improvement!:

        [bobg at box6 ~]$ free -m
                      total       used       free     shared   
        buffers     cached
        Mem:          3022        719       2303          0        
        31        265
        -/+ buffers/cache:        422       2600
        Swap:         4575          0       4575

    This is an up to date F-15 32 bit configured as I want it.

    [bobg at box6 ~]$ uname -a
    Linux box6 2.6.38.8-35.fc15.i686 #1 SMP Wed Jul 6 14:46:26 UTC 2011
    i686 i686 i386 GNU/Linux

    Must I install the 64 bit version to take advantage of the memory?
    If so perhaps I could upgrade the present install to 64 and keep my
    configuration or do I have to bite the bullet and do a new install.

    Bob

    --