hey Namja... I just started my repaint a few days ago..
I did not bother with primer. I got a few cans of RustO from the home store and painted. Put on about 5 or 6 light coats and have no issues. IMHO, sanding and priming is fine and all for a car or something in a high traffic area but, for a pc case its kinda overkill. I'm getting the thing re-assembled now. I went with satin black inside and gloss red highlights, with a gloss clear coat.
All in all very easy.
After removing the pop rivets, I toyed with the idea of reversing the mother board layout so that the CPU is on the bottom. I have a Lian Li case that has this layout and I really like it. However, it would have negated some of the original air flow designs. Maybe when/if I switch to water cooling i'll consider it again.
attached are some before pics after i removed the drive bays