i have 6Gb of memory in my machine, and i’m running 64-bit kubuntu.
the motherboard is an asus p5q, which, according to the dealer, is 64-bit compatible.
there’s 256Mb of memory on the graphics card.
the output of lshw is the following (notice how it says ‘width 32 bits’ for the entire system, although both the memory and the cpu are listed as having ‘width 64 bits’):
box
description: Desktop Computer
product: System Product Name
vendor: System manufacturer
version: System Version
serial: System Serial Number
width: 32 bits
capabilities: smbios-2.5 dmi-2.5 smp-1.4 smp
configuration: boot=normal chassis=desktop cpus=4 uuid=E0A5FB01-54D0-DD11-8C6D-00248C031C33
…
*-cpu:0
description: CPU
product: Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz
vendor: Intel Corp.
physical id: 4
bus info: cpu@0
version: 6.15.11
serial: 0000-06FB-0000-0000-0000-0000
slot: LGA 775
size: 2400MHz
capacity: 3800MHz
width: 64 bits
clock: 266MHz
capabilities: boot fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx x86-64 constant_tsc arch_perfmon pebs bts pni monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr lahf_lm
configuration: id=1
…
*-memory
description: System Memory
physical id: 3a
slot: System board or motherboard
size: 6GiB
*-bank:0
description: DIMM Synchronous 1066 MHz (0.9 ns)
product: ModulePartNumber00
vendor: Manufacturer00
physical id: 0
serial: SerNum00
slot: DIMM0
size: 2GiB
width: 64 bits
clock: 1066MHz (0.9ns)
*-bank:1
…