DDR2 800 memory will work, but only if you are not putting it in with an existing DDR2 667 memory module. The memory modules installed in a system must match.
thanks for the respond and I'm not mixing memory I'm only putting in one because currently only one of my slots works. I'm also trying to find some information on the memory that I'm about to purchase (Kingston KVR800D2/2GR 2GB PC6400 DDR2 800MHz) to see if it has compatibility but no such luck. Jaquith where I live all can get is the 800mhz.
Kingston like Crucial produces their own IC's for that more than likely you'll be fine, and both are good about offering a variety of Frequencies and CAS. Worst case, PM me or start a new post if >few days and the Kit can be manually set if needed to work.