Unisim versus Virtex2 Xilinx Library

Hi,

  I have seen a piece of code in which there is elements such as FDP,
BUFG and DCM. This code is to get different clocks from internal
reference clock. I have simulated this but I cannot. These elements
uses virtex2.FDP, virtex2.BUFG, ... so library virtex2 is used. My
board is Virtex II Pro, so could I use this library?. I suppose that
yes.

My question is about unisim and virtex2. Are these libraries similar?.
Virtex2 is obsolete and now everyone use unisim.

Best Regards

Pablo