It's always worth to have a little tube of silver-based heat paste. That's what, $8 per tube, and it's always kind of disappointing to find you got all your components but miss/run out of paste.
The only thing to think of on top of the list is maybe a wireless NIC (if you don't want to use ethernet cables), plus a card reader if you need it.
Motherboard choice: what pevergreen said, although you can augment your choice with a little rationalisation by reading a couple reviews and seeing if there are any significant (BIOS) issues. Google is good for that. There are a few pitfalls of course: USB 1.1, only 2 slots for RAM.
Apart from looks, as far as cases go it is mostly checking the motherboard fits in the case (in this particular instance you would check for a case which supports Micro ATX). Bonus things are air filters (definitely worth it, but not on cheaper cases usually).
Bookmarks