I agree with what everyone has said so far, although if you're not interested in overclocking at all, then I wouldn't bother with the different heatsink (freezer 7).

PSU wise, Corsair ones are good, but so are Antec ones in my experience. Definitely go for a main brand one, they aren't something to skimp on. I have the Antec Neopower 650W (modular), and it's been great.

If you are going for a new case then this automatically becomes a new build . But yeah, you'd have to decide first whether you want something with a window and lights etc or a more sleek silver type thing.