First off, Quad SLI is a total waste.
Nvidia is not truly interested in their dual GPU single slot solutions meaning they do not offer the level of suport they should for them. They only offer them to counter ATI's X2 card. There are not any games out there that would benefit from more than 2 GPUs anyways. Anything more is just wasted power. Add to that the next generation of nVidia and ATI cards coming out in less than a month and it comes out to a very bad choice.
2nd, why would you want to spend $1500 on a CPU? You can get the same level of performance from an overclocked Q6600 for around $250. Hell, you should be easily able to push the Q6600 to 3.6GHz or higher. Just pissing cash out there.
3rd, do you really need a Blur-ay burner? You can get buy just fine with a $25 DVD/RW.
Not saying that it wouldn't be a smoking rig, but you are wasting quite a bit of cash where you need not.
There are many high end games that utilize quads as well as new games coming out and believe me SLI works great. Make sure you get a 30" LCD so you can take advantage of all that power and if you can afford it go for it.