thanks for the reply but the wiki page mentions nothing about media, the 'helper application' is labeled as i386 (i run an amd64) and all the pic links are broken. So unfortunately it did not answer the question....
Upgraded my core a couple of hours ago from beta4 to RC1 without any major problems.
I use AMD64 so I downloaded the AMD64 single-layer DVD.
Booted it and chose preserve settings and keep /home directory.
As long as you have all media and other things you want to preserve under /home you should be fine.
Otherwise make a backup of the stuff you want to keep or just move/copy it to /home.
The only problem I have seen so far is that all software in "Add Software" like libdvdcss etc was not preserved.
Once I reinstalled those I was fine.
This is my personal experience so far. It may vary depending on hardware configuration I guess.
My core's hw config:
ASUS M2N-VM DH motherboard with 2GB ram and a 4400+ cpu.
I use the integrated nvidia 6150 graphics without problems.
250GB Sata drive attached to the jmicron integrated controller as a system drive for lmce.
4 other sata drives on software raid attached to the builtin nvidia controller. (did not dare to have those connected during upgrade).