Well if you want an extremely powerful system, and you don't want to spend LESS than $2,000, there are alot of options. Take a look at these links:
RAM (Buy Two of these for 8GB)
- $75.99 (x2)
Video Card (Buy two of these and SLI them together)
- $134.99 (x2)
Keyboard and Mouse
That should be all you would need. If you are going to swap anything out, make sure that it is compatible with the Motherboard you will be getting. That should be a rough idea to get you started though.
Sub-total = $1642.88
Tax (at 5%) = $82.15
Total = $1725.03
Look at that! Even under $2,000! Remember that you will need an OS though. I'm not sure what you are using right now, but you will need a 64-bit version of Vista or 7, whichever you choose. You can find the Operating Systems under the software section of Newegg
Also, if you want more LED lights, you can always buy them and put them in yourself to make it more flashy.
That should be a start though. And that computer will waste alot of others.
Also keep in mind that the CPU Fan I listed there is Optional. The Processor above comes with a fan, but with all of the components that will be in your computer and the possible stress on the cpu, a powerful fan will help the overall temperature of your computer.
If you want RAM cooling, just look around on newegg as well. Wouldn't be a bad idea if you have the money to spend, but it's also not completely necessary.
Good luck! Like I said before, if you are thinking of swapping components, be sure they are compatible. If you aren't sure, post the link of what you would want to put in and someone (like myself) would be glad to help you.
Also if you want more case fans, just look on the site for some and make sure they are compatible with your case. The case comes with three fans already, but maybe you have different preferences (you can probably find some with some LED's on them.)