D630 memory and media bay options question

​Hi,​

​I recently got a D630 to replace my D610. I'm loving it. The D610 has 2GB PC4200 memory and a second hard drive and a second battery for it's media bay.​

​I'd like to know if the media bay devices are compatible with my D630. also, there's 1GB of PC5300 memory in the D630 now. Would 2GB of PC4200 work ok, and would it be an upgrade or a downgrade? ​

​Thanks, Mike ​