Hi there,
to answer your second question.......
In window exp index, memory score just the same 4.8, after add another 2*1 gig kingston ddr2 667, it is normal?
My info regarding the Windows Experience Rating is, I admit, a little old now, but I know that when Microsoft first used this in Vista the Maximum score for RAM was: <1.5 Gb's = 4.5.
Now I know that they have tweaked with the W.E.I in Windows 7 but I am pretty certain that this same condition applies.
eg: If you have 2 gig of RAM and your rating is x.8 then adding another 2 gig would make no change to this rating it will stay at x.8. Basically, to increase the score above x.8 you would need faster RAM. (to be honest things are a little more complex than this but not sure how deep you want to go).
By thx1138: it depends a lot on what you hope to improve the PC for - gaming, image editing, or simply start-up and program-loading times
Have to fully agree with this. Could you let us know what you want from your PC, and or, why you think there is a bottleneck?