But the thing is I have no more PCI slots.
Where can I get a great motherboard with i7 975 support and with enough PCI slots to support all my adapters?
And if there is any thing i can do to make it go faster (perhaps overclock to 4Ghz!?) or better video or sound card?
And secondly-
Should i buy the Alienware Area-51 ALX or should i build my own custom designed PC and then put in the SSD?
You might get slightly better performance from 12GB of ram (2GBx6), as the memory speed will be higher, and 12GB is already extreme overkill. I would recomend Corsair ram.
As for video, I would go with twin 5870 cards if it was my build.
The sound card is nice enough, though you might be happier with something from HT Omega if you have the slots once you are all done with everything else.
For network, I know that the mainboard will have at least 2 gigabit ports onboard, but I would still drop the $25 on a nice intel adapter if wired networking will be used at all.
As for overclocking, you could go with a phase change cooling system that would push the chip to its theoretical limits, but these setups are very expensive (over $1000).
You forgot the power supply...I would go with a nice Corsair unit.
Also, the TV tuner card will end up being a big issue if you plan to use it with HD cable or HD satelite.
One other thing to keep in mind...Alienware was once a high-end PC builder catering to the performance croud. This changed when Dell bought them, and they now cut corners in order to save money...and they don't pass the saving along to you. If you want top-of-the-line, don't copy Alienware.
Your going to spend $6000 on hard drive(s) by itself? Thats a bit on the extreme side. If you truly have the budget, go for it, but atm Intel has proven to have the best SSDs on the market.