My thought would be on the computer side. Yet it isn't necessarily an easy decision.
What do you need for computing? What do you want to do? I almost always want more computing equipment, but it's always a bunch of trade-offs. How much more can I do with a new machine, and how much more time will I need to spend managing it? If a new machine is a replacement machine, then the doing and managing is probably not much of an issue. If it's an additional machine, then it's a matter of issues such as when and where are you going to use it, how much will you use it, how are you going to sync data across machines, and how are you going to configure the machine and keep all of the software up-to-date. Easy as some of these things can be in the Mac world, they still take some time and effort. While money can be an issue on some of these (duplicate commercial s/w licenses, for instance), time can be a more onerous expense.
Prior to my new refurbed MacBook, I had 4 machines - two towers, two laptops, all of which are dual boot. Like I really needed another machine and completely different operating system. -_^ So I bought the MacBook anyway.
Go for it. I'd go for the MacBook. Besides, what the heck? This is the Mac-Forums. You mean there's anything we should want outside the Mac?! :mac: