Question about RAM

I am thinking of purchasing some more RAM for my computer. Right now this is what I have:


[img]http://img6.imageshack.us/img6/3630/27915395.jpg[/img]

[img]http://img3.imageshack.us/img3/3348/28238571.jpg[/img]


I was wondering if I can have speeds of RAM on the same mobo. I have a NF650iSLIT if that helps.

XP or vista?

Vista x64

You're running 667mhz.. i'd get 4 gigs of 800.. it's like 45$ for the g.skill PI with the low latency and timings

with vista 64x i'd go with 4 gb of at least 800 mhz ..ram isn't as expensive as it use to be