Just a bit of helpful information in case the place you got your upgrade from didn't tell you and if these were all in one computer together. Your fastest RAM only runs as efficiently as your slowest. For this reason it is always best to have all of your RAM sticks the same speed to get the most speed out of the memory. The 667 1GB and the 800 .5 you have up here were forced to slow down to the 1GB 533 speed. Upgrading is always a good option but, seeing as these are mixed speeds they were not running as efficiently as they could have if they were matched up.
though the pictures arent showing up there for me at least, these should be ddr2 unless im mistaken (and that's not impossible either, not too informed on this) i dont believe ddr reaches into 667 or 533