I have a couple questions about my mac mini and RAM. Would i notice a huge increase if i were to put 2 GB of RAM in it? (i would be going from 1 GB). I have heard that the speed increase from 512 to 1 gig is much better than from 1 gig to 2 gigs. Also, so i don't void the warranty, can i just buy RAM from apple and have the genius bar install it, or do i have to install it myself?