I have a dual core processor..........its processor speed is 2.8Ghz......?

wil the processoe speed b divided into 1.8 4 each processor...............are the 2 processors virtual or r they physically present........if yes dus tht mean i hav 2 processors working wid 2.8 GHz..........if yes then dus tht mean i hav bought 2 PCs 4 the price of one?...........hw dus Core 2 Duo differ frm dis................hw dus pentium d differ frm these two ......and also pentium 4