Driver Heaven posted a review on the OCZ ReaperX DDR2-800 4GB & Kingston Hyper X DDR2-1066 2GB memory modules A quote from the article:

The DDR2 memory market currently has two major options for consumers using the latest CPUs. Consumers can either go for 2 GB kits of speeds up to 1066MHz, which are priced quite reasonably or 4 GB kits of DDR2-800 with tighter timings. What difference does this make to the latest CPUs and which option should the consumer go for when seeking the best performance?

Today we are pitting 4GB of OCZ's ReaperX DDR2-800 against 2 GB of Kingston HyperX DDR2-1066 in an attempt to answer the above question.

OCZ ReaperX DDR2-800 4GB & Kingston Hyper X DDR2-1066 2GB Review