I play around with a lot of stuff on my home computer. The problem with that is you end up with a lot of crap let hanging around after you've moved on from playing with rails or python or whatever.
Your system path has loads of otherwise unnessesary additions. You've had to install stuff. If you are on windows you might have done some terrible things to get that node package to compile.
It would be nice if you could somehow eat your cake and then not have to clean your plate afterwards. Welcome Vagrant.
Vagrant basically makes it easy to set up VMs and provision them. It is designed more for dev teams to be able to set up and share their run-time environments so no-one need ever say "It work's on my machine" ever again.
In my case I can boot one up install whatever and do a bit of this and that. Ideally I will end up with a couple of base boxes that have my preferred setups for doing php, nodejs etc, keeping my actually machine nice a clear of all the additional installs.
I'll do a few post on how to set up Vagrant but they are well covered in the Getting Started docs.