I see there are two internal SATA connectors on the interior of the card. What is the purpose of this? Does it speed up transfer to the HDD?
Take a look here:http://serverfault.com/questions/11633/whats-the-bandwidth-and-form-factor-for-pcie-x1-x4-x8-and-x16
The PCIE X4 slot provides approximately 800MB/s of bandwidth. The purpose of the internal SATA connectors are if you need extra SATA ports (say if you have a lot of SATA HDD's, and need more SATA port connections). It doesn't necessarily speed up transfers. However even 2 HDD's would never fill up that bandwidth (it would be close to around 300MB/s).
Basically only get this if you need USB3/ and or need extra SATA ports. It's actually quite a nice card.