I think it comes down to making a decision about whether you want it portable or not, whether you want to keep it or not. I made a decision to overcapitalise on my white macbook. Yes, its old, yes, its out of date, and not as speedy as the more modern machines, but it does what I want it to.
Thunk about whether its worth that, to you. If I were me, I would probably spend the money.