Maximum PC

I currently have 512mb (2x256) DDR400 memory on an Intel D865PERL. I want to go to 1024mb, would it be better to replace my 2x256 sticks with 2x512, or just add 2 more to make it 4x256. or would it even make a difference which way i go?

well, its a matter of preference more than anything else. no matter what people say the difference in speed between 2.512 or 4x256 wont be noticeable in day to day usage. it would probably be cheaper to get 2x256 mb sticks tha 2x512mb sticks.

If you're heavily overclocking, having 4 sticks can (and most likely will) affect your success. You also introduce more chances of having a bad stick, either initially or developing over time. That's nitpicking however, and the costs of replacing 2 sticks can't be overlooked.

There was an article posted not that long ago where someone benchmarked 4 sticks versus 2, and the 4 performed slightly better. That's the first I've seen of benchmarking such a scenario. I agree w/ the above poster though, that the difference is negligeable.

Running PC3200, my hunch is that you're not overclocking, so by all means, fill up those slots and save yourself the expense of needlessly replacing your existing dimms.