I'm looking to move up to 8GB and I'd prefer to go with a 2 stick kit instead of 4. I think I'm lucky though and may have just got the last 2x4GB kit of DDR2-800 CL5 memory that Newegg had. It was in stock, I ordered it, and now it says it's shipped, but the product page now says it's out of stock and discontinued.
Based on your last statement that DDR2-800 CL6 and DDR2-667 CL5 have the same latency, I take it that it the DDR2-800 would be better. Hopefully I won't have to worry about that though.
Thanks for the response.