No, you can mix and match rams of different speeds..the performance of your ram will be determined by the slowest module you have installed.
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CPU - E6400 Core 2 Duo @ 3.2ghz
Cooling - Zalman CNPS9500
Motherboard - Asus P5W DH Deluxe
Memory - OCZ PC2-8000 Platinum XTC 2GB (2x1024MB)
Video - BFG 8800 GTX OC
DVD - LG Super Multi
HD - WD Raptor 36gb
HD2 - Maxtor Diamondmax 10 250gb
PSU - Corsair HX Series CMPSU-620HX 620W
Case - Cooler Master Centurion 5
Sound - Creative Sound Blaster X-Fi Fatal1ty FPS |