Here is dilemma I`m facing with my PC which is a HP m7350la model. I feel like upgrading its RAM for the new Windows operating system coming, Windows 7, and also making it more efficient.

I read in the product configuration of this specific model that(

Component Attributes
Memory Installed 1 GB (2 x 512)
Maximum allowed 4 GB* (4 x 1 GB) requires the replacement of the installed 512 MB DIMMs
*Actual available memory may be less
Speed supported PC2-4200 MB/sec
Type 240 pin, DDR2 SDRAM
DIMM slots Four
Open DIMM slots Two

But the manual for Kingston memory says that (

DDR2 speeds launched in volume in 2004 include 400MHz and 533MHz DDR2. 667MHz DDR2 launched in April 2005. DDR2 is expected to be the dominant memory technology in the second half of 2005 and become the mainstream memory technology through 2007.

I`m all confused now. Any feedback, suggestions, comments are welcome.

The only important fact in obtaining memory is the PC2-4200 label. Go to the shop, buy the RAM with that type description and all should work OK. The rest is just confusing blurb that doesn't help you get anything faster or better.