mac's are better for sure in terms of quality but more expensive so if it is just for personal use maybe a windows is fine
For laptops, best quality I have seen are Dell's higher end business models. Built very solid and the one I bought for college about 6 years ago has never had any real problems.
For a desktop, either build your own or add a video card to a rack server. It's pretty easy to end up with something that will run great under heavy load, as long as you don't skimp on the cooling or power supply.
Software wise, I suggest some form of Linux (Ubuntu recommended for beginners) and install Windows and/or OS X in a VM if you need it.