Usually reserved for overclocking, your machine does not offer such an adjustment.
I would get the pairs and see what Crucial.com offers.
-> In closing I advise that you stop at 2GB RAM due to the OS you are likely running will limit any application's memory to just 2GB. There was little gain on XP past 1GB so 2 is just fine.
I have a HP Media Center m495c desktop. The motherboard is a ASUS P4SD-LA PES revision 0.01. I want to install 2GB of RAM and I am curious if the MOBO will support dual channel RAM. It takes DDR400 PC3200 RAM. I was also wondering if it was worth looking at RAM that comes with a heat spreader? I tried looking on HP and ASUS websites, but I couldn't find any info as far as supporting dual channel. Thanks for your help.