all of the dm1- 4000 series are the same apart from either a 320gb or 640gb hard drive. (i found a internal hp spec sheet detailing the 4000 series as a whole and that was the only difference.
i think that you will also find that these laptops come with the HD6320 not the HD6320M as the M only has shared memory and the HD6320 has a dedicated 384mb + can run shared as well
although i have not worked this out yet.
one other thing can you check you product code under the battery and tell me if your **** bought laptops are actually DM1-4027ea not sa ive spoke HP and they have stated that currys should not of been selling the ea spec ones as they are entertainment computers with slightly enhanced audio and some other internal features. HP also said that the sa stands for standard as in standard model.
now go check the HP barcodes on the boxes