Don't be fooled if someone tells you it's easier to install software on a certain platform. It can be a huge misconception. The general consensus is that installing software on Windows is usually the most complex. This is probably because practically every piece of decent software needs an installation wizard of some kind. However, this approach is actually among the easiest. The user downloads the software and runs the setup file. After a while, every thing magically appears where it should.
Installing software on a Mac is actually complex, although most of the time it is either a wizard or a drag-and-drop operation. This drag-and-drop part makes it easier than Windows, but when it comes to removal, there might be a lot more work later on..
Installing software on Linux depends. If there is a ready binary, you will probably have no problem. If there isn't, well it will be slightly more complex than Windows and Mac, depending on whether you have the dependencies needed. But then again, what would a Windows user do with source files? :D (assuming they don't have a compiler, that is, how many Windows users actually have compilers installed?)