Problem with computer

Ok, the topic title isn't too clear so I'll try and explain as best I can:

Firstly, Im not using the PC I have problems with so no wise-guy comments please :P

When I turn my PC on, it usually beeps then starts running, however, the beep doesn't occur any more, everything is the same with the PC but it started cutting out half-way through working etc, and now it won't even run.

I have tried searching the internet to find a cause for this and the main reason seems to be a motherboard fault (can anyone confirm this?)

Now the specifications of things are as follows:

I have a 'Socket A' motherboard with G-Force 4 GFX Card (64mb), 256mb RAM (DDR) and a 20GB Harddrive.

The question's are:

Is the motherboard the problem?

Can it be fixed?

Could I buy a new motherboard and keep the processor and heat sink?

If I was forced to buy a new computer, is http://www.aria.co.uk a good place to buy from.

Im hoping to fix the computer for as small a fee as possible, a perfect scenario would see the computer fixing itself but hey, what are the chances of that lol.

Help would be much appreciated, to be honest im not too good with the old computer things,

Sorry if this problem has been posted before, its been a while since I last logged on :wink:

Thanks in advance!

Peace.