As said already, a Corsair 400W would suffice for your build.. However, its always good to have headroom when it comes to a PSU selection.. Helps in moving upto bigger and better things in the future.. Keeping that in mind, i'd suggest you to get the Corsair VX 550W if it fits your price bracket..
P.S. - Do not count on the core unlocking feature.. They sometimes work and sometimes don't.. Go for a true quad instead.. Check out the Athlon II X4 635.. Its pretty decently priced..