وهذه معلومات اضافيه وجدتها مهمه للاستفاده
What is RTM, GA, Retail, and OEM
RTM is when the code is completed and signed off. GA, or general availability, is when that RTM'ed code is finally made available to the general public. Even though there is a full three months between RTM and GA, there is no difference between the RTM code and what you get when you get Windows at GA. The RTM bits are the GA bits. RTM is "we're done with the code", and GA is "we're done with the packaging, distribution, marketing, etc., and are read to sell it".
When GA comes, you can get Windows in two flavors: retail, which is what you buy at a store, is a less restrictive license (you can transfer it between machines, as long as only one machine is activated at a time), and you are entitled to support from Microsoft. OEM is a cheaper license, that you get when you get Windows bundled with a PC or if you buy a "system builder" copy from places like Newegg. OEM is cheaper because it's locked to a system (you can't transfer your license to another machine), and you are not entitled to tech support (the person who built your computer is responsible).
Generally speaking, there are two types of OEMs: regular and "royalty". Regular OEM is what you get when you buy a "system builder" OEM Windows. Except for the label on the disc, regular OEM discs are the same as retail discs, and they install the exact same bits as a retail disc. The difference is not in the disc, but in the key: if you activate Windows with a OEM key, that key is forever tied to your system, whereas if you use a retail key to activate, you can move that activation to another computer in the future.
The big PC makers like Dell, HP, and Sony are classified as "royalty OEMs" by Microsoft. They will often customize their disc by including logos, extra drivers, and/or hotfixes. Their discs will also include a special certificate that Windows uses to authenticate your computer's BIOS (which lets the royalty OEMs use something called SLP, which sorta allows them to bypass the hassle of activation).