Wow, 500W PSU! Not bad for that era at all. I really hope this helps but... Maybe try out the dohickey heat sink that Halo posted if the new case doesn't work out as well as you had hoped it might. It sure can't hurt.
Everything that irritates us about others can lead us to an understanding of ourselves. -- Carl Jung
eVGA X58 tri-SLI, i7 930 @ 3.8GHz., Corsair 6GB Dominator, Inno3D GTX470, eVGA260
ASUS P8P67 Pro, i7 2600K @4.60 GHz, 8GB RAM, eVGA GTX 460