Both of those cards are bootable once you flash the firmware to the EFI version (can get it off of the disk that comes with it, or off of the support site).
Between the two, the Areca is a better choice (better price/performance ratio;
includes internal cables, which are about $30USD each if you have to buy them, so it saves you another $60 or so as well as the price difference between the models).

Provantage is a good site, has great prices, and even ships internationally (
Areca ARC-1880i).
You'll also need a mount of some sort (MaxUpgrades has a kit that will fit 8x 2.5" SSD's in a single optical bay - it also includes cables to get power to the drives;
here).