If you keep the faster RAM in and then add the slower RAM, your system will slow the faster RAM down to match the slower RAM. It would still increase your capacity.
Wish I could do that. I've been saving for a Javelin for 6 months now and I'm still not there, ha. Just $550 to go.
I did just spend $600 on a Nova tank but it came with a free A2 ship to carry it in ;)
Curse you Nova tank!