USB 3.0 is a worthwhile upgrade. Startech do a range of cards that will suit your purpose. These are based on the NEC controller, which while pretty good, isn't as good as an intel controller. Unfortunately, I do not know of an add-on card which has the intel controller, only motherboards.
SATA 3 is a bit more questionable. The problem being that only SSDs are capable of saturating the SATA 3 interface. Mechanical hard drives still don't come close to saturating the SATA 2 interface. You would also have the problem that if you switch you OS drive to the add-on card you will quite likely have to re-install your OS as well.
To get even close to SATA 3 speeds with a PCI-E card you will need at least an x4 slot. I'm using one in a x4 slot and am getting 380 mb/s with a SATA 3 SSD, so a x1 slot will likely be slower than SATA 2. I did not have to resinstall the OS, I just loaded the drivers, inserted the card, and selected the card in the bios boot order. I am also using PCI-E USB 3.0 cards, and while I have not tested them for speed, they are definitely faster than USB 2.0.
I bought two separate cheap usb 3.0 cards with an internal header (one is HooToo and I forget the other), and they are both working fine.