RAM Upgrade

Wikipedia: "DDR2 SDRAM or Double-Data-Rate [2] Synchronous Dynamic [RAM] is a computer memory technology. It is a part of the SDRAM family of random access memory technologies, which is one of many DRAM implementations." The Kinston Technology site seems to recommend a special path for Dell Inspiron 5100: namely: KTD-INSP8200/512 x 2, but (see below) I'm deciding to go with the "Kingston Value RAM" (i.e., generic) chips.

I've been struggling with infernally slow booting, skipping playback of music, etc. Maybe it's the RAM. Currently I have 384 MB.

Boosted RAM to 768 MB. Misinformed by supercilious Circuit City salesman that KGT KVR333SO512R costs $100. In fact only $34.99 (i.e., $64.99 - $30.00 rebate). This is the 512 MB 333MHz Kingston chip, not the 512MB 533 MHz. New module definitely made the Inspiron 5100 run more smoothly. Second module: accidentally picked up the KVR400SO512R, i.e., 400 MHz version, 5/9/06. Will this cause compatability problems with other 333 MHz module?