You have DDR2 800Mhz RAM and you want to upgrade to 1066Mhz? Not a good idea. There's not going to be much difference in speed and these days, due to availability issues, DDR2 already costs about the same, if not more, than DDR3. If you really, really, really need faster RAM might as well buy a new system utilising DDR3 that way you can use 2000Mhz DDR3 RAM.
9xer .... Thanks, that's what I was thinking. I really don't need a new system. I have the opportunity to upgrade processors. The T6600 runs 2.2 mhz with 2 mb of L2 cache whereas the T9550 runs at 2.6 mhz with 6 mb L2 cache. It's a $55 upgrade.
Figured I should get some benefit. Just wanted to make sure there was no instability with the setup?
I don't see any instability problems. Unless you're doing some really processor-intensive stuff (like crunching numbers), I doubt you'd notice any improvement in processor speed, as your current setup sounds pretty fast already.