One program, there is little to no gain past 2GB. Read about the /3GB BOOT.INI switch and more about your issue. Check with the machine's maker for supported configurations and if it's supported check the BIOS version.
My son-in law wanted to add memory to his HP Vista home premium machine.He wanted to end up with 3 gig.
He had 4 512mg sticks so we removed 2 of the 512s and replaced them with 2 1 gig sticks for the toatl of 3 gigs.
Everything went fine except he lost the duel channel memory and it went back to single channel?
The memory is from the same manufacture (Kingston) and the same speed pc 3200 KVR400.
We tried every combination but could never get the 3 gig to come up duel channel.
We can remove the 2 1 gig stcks and re-install the 512s and it comes right up as duel channel.
The question we have, does duel channel really make that much difference over single channel or would the extra 1 gig of memory be better?
It is for his home/office computer but he does play Flight Simulator X on it.