one do not use caps in a title. there is no need to shout.
to answer your question it depends on you apps. if you are gamer which i suspect you are. it is best to have 2 x 1gb stricks of ram. that way you can run it at a 1t command rate which gives a good boost. 3-4 megs probably won't hurt but isn't necessary.
Does it really make a difference if you have 4 sticks of 512mb or 2 sticks of 1gb? even if they both have the same latency and timing?
such as on the Corsair XMS:
Cas Latency 2
The correct answer is to go to Everest 2006 and run the memory latency test.. Nearly all 1gb per stick of ram stink on latency. The very best like Mushkins Redline 3-2-2-8(no longer availble) is about 55 ns. Average of the Samsung UCCC memory is around 65 to 75 ns, Infineon is more like80ns. The very best TCCD or Winbond will do sub 40 ns. That difference is the difference between about 44100 on whetstone with a opteron 165 at 2.44 ghz for 2x1gb of OCZ DDr400 gold and 50500 for the 4x512mb. Memory is Mushkin blue level WinbondUTT BH-5. 2x512 with Mushkin Black Level II wiill do about 51455. Bandwidth also changes. At 274 Fsb the 2x1gb is about 5850mb band width vs. 6245 mb for the 4x512mb. You do pay about a 3% penalty for 4x512 vs 2x512 due to the change in command line time between 1 t and 2t. I don't know what memory modules you have on the corsair but it is very unlikely to be eiter of the TCCD or Winbond. So your results will vary . More than 2 gb of memory is going to run into problems with windows until Vista comes out. XP does not recognize more than 3.5 gb of memory and can't use more than 3gb operationally. On A64 platforms most 2x1gb memory is not stable under full load at 1t. It will run 1t under less than about 75% load. So the 1t/2t issue is a red herring. The higher the rated speed the higher the latency is going to be and the lower the band width is vs PC3200 at the same speed. You do have to recognize that most PC3200 except TCCD will not run more than about 250-260mhz stablely. So 300mhz memory will catch up on bandwith but with increased latency. There is no free lunch.