These things are not a huge concern now. All monitors sold by Rainy Day conform to modern standards. Energy Star power saving methods, forced into the industry by the US government, and now standard fare in many components. Basically they go into power-saving mode when not in use for a period of time. Intel makes the Pentium series of chips, while AMD makes the Athlon, and Duron, and IDT makes the WinChip Cyrix no longer makes CPU's.
Some people have a preference for one or the other.
If price is any consideration, look at the AMD chips. They are very reliable and significantly cheaper. OS Windows Linux operating system OS some software that makes your computer useful. Without it, you would not be able to use any other programs. Windows programs such as Microsoft Office or Microsoft Internet Explorer will not run under Linux.