Hi
Welcome to MR.
Please try the Forum's Search function - this question has been asked and answered many times before, including 1 hour ago...
The OCZ RAM at 800 MHz may work in Core2Duo products. However there will be no speed increase, because the Mac's memory controller is limited to 667 MHz, so there is no point in buying 800 MHz RAM. The vendor (NewEgg) does not guarantee compatibility, and they have a restocking-charge policy on returns. Plus this is far from the best price.
On MR, the most often recommended vendors are Crucial (use the link at the top), OWC (Macsales.com) and
Data Memory Systems who have a guaranteed compatible 4 Gb kit for $238 with a free shipping option, and great customer service.