Get a good fan with some good grease. ****ty fans = Overheating. You should be looking to pay about $10 for a half-decent fan.
As for case modding, I suggest carefully unscrewing everything from inside yer computer (making sure to maintain all connections, or maybe using come kind of Sticker-A to Sticker-A thing to reattatch everything). Then just get some power-tools.
A good start is to buy loads of high-intensity LED lights, the kind of faded-source ones so the light looks more atmospheric than projected.
Get tons of fibre-optic cables (the see-through kind, not the data-carrying kind) and loads of sticky-tape.
Install a seperate battery and switch for all your lights and ****.
Hack **** out of yer case using the powertools and cut some holes in it all over.
Spray-paint it with a vynil or some plastic-based, tough-wearing, heat resistant paint. Install all the lights using the battery and the stick-tape.
Re-install all your components.
Wrap some fibre-optic cable around all the edges of all the holes you make and set some up so it looks like glowing circuitry if you want. And get some rubber-edging as well so there are no sharp-edges exposed. Then get some high-quality perspex and glue/screw/bash it over the hole from the inside.
Turn it all on and make sure it works.
Be happy.
Take pictures.
Post pictures on HLP.