That Corsair looks ok,
anything between 400-600w would be find for what your doing.
only thing to consider is the PSU you can remove and use in your next PC build. so going a little more powerfull now may mean you dont have to buy another so soon down the track.
you will have to stick to the measurements of a standard ATX PSU tho, (sorry no 1200w monster for you)
Measure your current one to make sure its a standard size. then your good to choose any standard sized ATX PSU
Dimensions of an ATX power supply are 150 mm width, 86 mm height, and typically 140 mm depth, although the depth can vary from brand to brand.http://en.wikipedia.org/wiki/Power_supply_unit_(computer)