That's a very nice PC. Vista home premium or basic?

It seems good to me, and not that badly priced actually...

Im thinkin about buyin this card, and it says that I require a:

450 Watt or greater power supply with 75 Watt 6-pin PCI Express power connector recommended

Now, Im not sure what this is as Im a PC n00b, but do I have to buy something? I don't quite undertstand.

Thx.