New computers

Hi there guys,
perhaps I don't get any support on this topic,
but hell, I give it a try
My brother and I will be working in the holidays for a new computer.
But our dad recently said, it is possible that I buy the computers for you and you pay me back after you worked.
We definetly want to buy our computers earlier,
but our parents are very moody, so we can actually only ask it when they are happy.
But we kind of need an excuse to convince them to already buy them, something as: our computers don't have the requirements for this or that program...

So in short:
Do you know an excuse that sounds convincing enough to let my parents make the move, to buy our computers in advance? =D

Thanks x)

just said that u can play silkroad better with a new computer.