My experience with Geil is that they're not reall good OCer, unless you buy ram rated at the speed you want to OC(dont expect DDR400 to run much faster!)
If you buy a nice case, you wont need to add any fans...Do you have any in mind?
As for video card, for video encoding you dont need anything fancy! and for a media PC you just need to find one with all the connection you might need.
Asus P4P800DX, P4C firstname.lastname@example.org, 2X512 OCZ PC4000 3-4-4-8, MSI 6800Ultra stock, 2X30gig Raid0