x1950 and dell e521 sata

I just bought an x1950 to replace the integrated graphics on my Dell e521. The card came without a power cable. (My first graphics card that requires real power. yeay) It tells me in red ascii letters when I boot the computer that there is no power cable.

My e521 is AMD 64x2 but I usually only run 32bit windows, I have 1 gig of ram (soon to be at least 2) and 300 watt power supply (soon to be 400).

I have sata drives and cables.

I searched before buying this card to see what would fit physically and be a good match for the pc I have. Since Dell did not make anything very fancy available from the factory, I chose to find someone who's put one of these in a computer like the one I have.

The card fits nicely, but I do not see a fitting on my sata style power supply to plug onto the graphics card. (sata is weird and Dell is cheap. do you need a dedicated power cable for each sata device? I have two unused on MB, sata 3 and 4)

Is the card I bought a good match for the computer? Where will my bottleneck be?

Hoping the power supply thats coming has connectors like this.

The one on the card is 2X6. Here is the PS I bought:

4X Peripheral Power Connectors for standard IDE (Parallel ATA) hard drives or optical drives
1X Floppy Drive Power Connectors
1X 4-pin ATX12V Power Connector
2X SATA Power Connector
1X 20pin/24pin dual-use Main connector