Viper,
LED's can be replaced. Although, depending on where they are installed (a fan for example) it's harder to disassemble the fan and install a new LED than to replace the entire fan. Lighting for CPU's is generally cheap, ranging from $2.99 to $15 for all sorts of lighting. Here is a site to check out that provides good lighting options... http://www.xoxide.com/lighting.html
As for running it all day, essentially, any well built lighting case should be made to do so. Yours is no exception. Your LED's have a "usage life." As a standard example, let's say your LED's can last up to 15,000 hours. So if you leave your CPU running while youre not home, it'll still be using those LED hours. It's all preference really. I find replacing lighting is extremely easy and cheap so I let them run with my machine all day long. To give you a time frame, a bulb that has 15,000 hours of life can last 625 days. Id account for temps and Id also assume you wont get a full 15K out of them so maybe 600 days. Thats a good chunk of time.
Also, you may want to look into Cold Cathode lighting. It "burns" a lot brighter and longer. Youll need much less of them to get the desired effect you're looking for. The "blue bars" in the front of your machine may already be Cold Cathodes. You cannot replace bulbs or anything with these, after they burn out, you must replace the tube, which generally runs about 8 bucks.
Any other questions, please let us know. Hope this helps.
~Trezier
