When deciding what motherboard to go for here are a few top tips:
1. What is the maximum size of memory it takes and what type.
2. How many PCI slots does it have (now a days, it's good to have at least 3).
3. Does it have onboard graphics, if it doesn't then that means you need to buy a graphics card before you can get it working.
4. Does it have AGP or PCI-Express, we would recommend that yours with a pci-express slot, since all the latest graphic cards are moving over to PCI Express.
5. The final and most important question: what socket type does it take, this will tell you what type of cpu you can install.
CPU
The CPU is the brains of the computer. Sometimes referred to simply as the processor or central processor, the CPU is where most calculations take place. In terms of computing power, the CPU is the most important element of a computer system.
Our Top tips
1. Remember AMD & Intel have different ways of measuring the speed of their products. So the best way to compare is by using the following website www.amdcompare.com .
2. What type of Heatsink youre going to need (the heatsink sits on top of the cpu and allows it to cool down)
3. Check reviews of the CPU, just type the model number into Google and you should be able to see the general view
of how good it is and for what market its intended on.
Graphics Card
The Graphics Card provides you with the capability to play games, get better quality pictures etc. However one thing we always like to remind our customers is before you buy your graphics card check the specification of the games or the software you need it for.
Also if you are buying a high end graphics card like the one shown here ----->
you need to make sure your power supply is powerfull enough to power it up. We normally recommend 500 watts.
Hard Drive
The Hard Drive should be one of your easiest choices to
make, since all you really need to know unless you are
really into your computers is, how big is it?

I would say for most gamers and familys 250GB will last you a life time.
The only people who need any more than that will be people who have a high end camera (over 10 mega pixel) and are wanting to save them on their hard disk.
I would suggest that if you, one day, decide to buy a new hard disk, check first to see what connections your motherboard takes (you can find this out by checking your manual or looking inside the case).
<--------IDE Connection
SATA Connection ----------------->