Im not flaming you harjun, but i suggest listening to what the people above here have said. Just think about it for a week or two and decide whether this is the right thing to do. Selling your PC is'nt the right thing to do btw. Eventually, you will miss it and would want it back. Plus, you wont get any of that money back, and you DEFINETELY wont be able to sell your laptop for over £700, with that kind of money, i could go out and buy a very nice fast PC with a monitor, speakers, and all that stuff.
Your tight bugget does'nt help either. £500 is a fair bit of money yes, but you will struggle to find a decent kart which will give you a hope in keeping up with the pack. Dont forget, you will have to replace tyres, will need fuel, spares, extra cash for any damage and all that, so really you need quite a higher bugget. So yes, either wait a week or two and think about it or save up the cash to get a better bugget and maybe sell thing you done use anymore (games for example). But for the love of god, DONT sell your pc. It will be a very silly thing to do after the money your father has put into it, and you will never get that cash back when it comes back to selling it.
@ everyone, lets stop the flaming now and go back on topic please.