You can use the same CD to make as many installations on as many computers as you like. After a little experience you may even wish to become a consultant. May cost you some money, but will be cheaper than Windows especially if you are planning to install Linux on more than one computer. Guidance of what hardware to purchase. Finding a vendor that will sell you a computer with Linux pre-installed is still not easy.
Many vendors are openly hostile to Linux.
You should use this option to get fixes and updates instead of complete distributions. Always get newest builds. Connection can be lost. Could be frustrating.