Yes, OEM is basically what is listed above.
Another thing is OEM products purchased from a retail generally means the retailer bought a (lot or 1000 units or more) of a specific product from a Manufacturer. Retailers won't offer any warranty on the product they sell, and the warranties or RMA's will only be done by the Manufacturer.
OEM products are usually cheaper then the retail version because of the manuals and extras...e.t.c.
One thing i'd never buy would be a OEM CPU. Sometimes they come with much less of even a Manufacturer warranty.
Operating Systems, soundcards, harddrives, optical drives... are all good OEM products to buy/