XPS 625 Upgrade

My GPU recently fried which, once replaced, was a huge difference (Nvidia 750TI).  It got me on a roll to try and update some other hardware.  I have a few questions below.  Any help would be appreciated.

I think this is a SATA1 mobo.  Will I be able to connect a PCI-e card with SATA3 connectors for a SATA3 SSD drive?  Will the PCI-e interface take advantage of the higher data transfer rates over the old SATA1 interface?

I have the Phenom X4 9850 2.5ghz.  Is there anything I can upgrade this to that Dell supports?