I built a speedy computer for a business customer onc, it was fast, and it has 2 PCI-E slots for SLI, so this should fit your needs:
motherboard:
http://www.newegg.com/Product/Product.asp?Item=N82E16813188006
CPU(different than what I used because my first one came without a heatsink):
http://www.newegg.com/Product/Product.asp?Item=N82E16819103537
Video Card(different card, same model):
http://www.newegg.com/Product/Product.asp?Item=N82E16814141018
RAM(dual channel RAM):
http://www.newegg.com/Product/Product.asp?Item=N82E16820141413
Hard drive:
http://www.newegg.com/Product/Product.asp?item=N82E16822144414
Optical drives:
http://www.newegg.com/Product/Product.asp?item=N82E16827106041(DVD Burner)
http://www.newegg.com/Product/Product.asp?item=N82E16827106992(CD/DVD combo drive)
Floppy drive:
http://www.newegg.com/Product/Product.asp?item=N82E16821103202
Case and Power Supply:
http://www.newegg.com/Product/Product.asp?Item=N82E16811129148
Not completely sure the Power Supply is enough, but give it a shot, if it doesnt work, buy a 400W PSU.
Total price: $475.38(American dollars)
As for the building, I will give you some steps:
1. Case Preparation-Remove all Hard drive cages, air ducts, and optical drive bezels.
2. Motherboard preperation-a. Install the CPU, by lifting the lever on the CPU socket, align the triangle on the processor and the socket, gently place the processor, it should drop in wthout any force needed. After that, install your heatsink according to instructions.
b. Install your memory-Insert your memory. To do this, simply align the key on the DIMM slot with the memory's key, and insert it that way. Close the latches in each side. Repeat for every stick of memory.
3. Insert your motherboard into your case-Place the standoffs you got with your case so that when you place your motherboard in, it will fit right in. Next, if necessary, remove the I/O panel(the silver thing where the mouse, keyboard, etc. plug in), and install the I/O panel that came with your motherboard. Next, gently place your motherboard to align with the standoffs, into your case.
4.Cable Connection-For this step, have your cables ready. Insert the 20+4-pin connecter into the power socket on the motherboard. Also place the 4-pin connecter with the motherboard, which adds stability. Also install any FireWire, USB, or other peripheral connection according to the manufacturer's instructions.
5. Install your video card-The video card powers all the display you see on your computer screen. Install this into a PCI-E slot(or other slot, depending on your video card's slot type)and screw in the screw. For AGP video cards, there are no screws. There is a latch on the slot. Close the slot.
6. Install your hard drive- Your hard drive is all the storage on your computer. Install this by taking a hard drive cage, screw in the screws connecting the hard drive cage to the hard drive. Insert the cage into it's place until you hear it *click* into place. Next, connect power and your SATA cable to the hard drive. For IDE hard drive users, set the hard drive jumper to "MA", which stands for Master.
7. Install your optical drives- The optical drives read CD's DVD's and other multimedia. The can also burn your CD's or DVD's for easy storage. To install this, screw the bezels into your optical drive, and insert it onto place. You should hear a *click*. Repeat for floppy drives and other optical drives.
Ok, the building is done. Now we install Windows and some drivers. Windows can cost $96.51 if you buy at ZipZoomFly.
To install Windows, see
HERE
Then you're done. If there are any problems, let me know.
sw123