Second Hand store computer

I seek opinions. I am looking for a computer that is mine alone so I can write undisturbed. So, I went to the second hand store looking for one and I found a dell pentium 4 with windows xp for 25$. I asked the cashier if they do returns and she replied "no". I then asked if they tested to see if the computers work and she said "I don't know". I am kind of cheap and afraid of being burned on 25$... So what do you guys think the chances are of it not working all together or just missing some RAM or something? Should I buy it?