You can build a very good computer (like above), for about $200 - $300 depending on if you you have old parts you can use.

I built this with from "barebones" computer kit which came with the following:

• Motherboard
• CPU Intel Pentiu Dual Core
• 2 Gb RAM
• 250BG Serial ATA Hard drive
• Case
• Power Supply 450W

I also had to purchase a CPU cooling fan, for about $20, since this kit did not include it - some do.

I used my old monitor, keyboard and mouse.
Actually, I used my old case too since it has neon lights, blue cables and a clear side.
I had to replace the old power supply with the new one, since the new board needed a bigger power connector.

Below are the steps used to build this computer - it works great and looks good too !

If you are moving your old system out of the case, back up all your data first. When I moved my hardware to another case, the disk drive
could no longer be read and had to be reformatted.

I initially loaded OpenSource SuSe, a LINUX operating system which worked well. This computer works with XP or
Vista too but not with Windows 2000. There are no Windows 2000 drivers for it.

I was able to purchase a copy of XP Pro for about $58 on line - prices vary.

Build Steps: (click on images for larger view)

Note: Only touch parts on the sides and only the plastic part. The parts can be damaged by static buildup. so be very careful.

1. Build the motherboard, adding the CPU, CPU fan and memory.

    Remove the socket cover on the motherboard and move cpu socket level up.

    Gently install the CPU, remove its cover, touching it only by the edges. Note the cpu slots - it only goes in one way.

    Add the heat sink grease that came with the fan and attache the fan. Spread the grease evenly. Make sure the fan fasteners     push through the board, as per the heat sink instructions.

    Attach the fan wires to the motherboard for power.

    Add memory. Gently push the memory board in the slot until the side fasteners lock.
    Put memory board in bank 1 first if have multiple memory cards

4. Connect the power cables, hard drive, CD and floppy drive.

    Each device has a data cable, sloted so it goes in one way, and power supply.

    You probably don't need to change the jumpers on the new hard drives but check the     hard drive documentation.

5. Install an operating system.

    This new board only has device drivers for Windows XP or greater. Open Source Suse     works on it too.

3. Install the motherboard in the PC case.

    Place the motherboard in the PC case to see where the hole on the board line up with the case.

    Place the brass colored posts, that came with the motherboard in the case where the motherboard holes line up.

    Install the motherboard, lining it up with the holes and side plate.

    Secure with the small screws and non-metal washers, that came with the motherboard. Do not overtighted - you
    can crack the board.