Keyboard power/ boot problems

Hey there,

I recently acquired an old desktop from a friend of mine and proceeded to take it apart.
After removing all the components from the casing and putting the RAM, GPU and HDD back (left the cpu in), and connecting it to power, it would pass the POST and boot into the BIOS. The problem is that no power is being supplied to the keyboard (I even tried the native USB ports) and it wont accept any input from the keyboard. I cannot enter the boot menu or setup menu due to this lack of input. Is it not loading the drivers for the keyboard? Or is it a power failure and the motherboard is now useless (I doubt the latter is true). Your help is appreciated .

Specs
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Dell Inspiron 530 package
Intel Core 2 Duo E2160 2.2 GHz
3GB DDR2 SDRAM @ 667MHz
Nvidia 8300 Gpu
Foxconn G33M02
Seagate Barracuda 7200.10 500GB HDD

 

Yes it did work before hand. After the POST it beeps once and there is a yellow/orange led indicator light as soon as the power is connected to the motherboard. after turning it on it shows a black screen with the DELL logo and in the corner "F12 = Options " and "F2 Setup"

 

The problem is that it is not powering the keyboard or accepting any input from mouse or keyboard. It won't even boot the OS (Windows Vista Home Premium). It only gets as far as the DELL logo (and stays there).