I checked several references. The ATI Radeon HD 4670 is not a power hungry video card. The Corsair VX 450 will easily power your new system.
Here is a link to a power consumption chart in one of the technical review:http://www.anandtech.com/video/showdoc.aspx?i=3405&p=9
Here's another one:http://www.guru3d.com/article/ati-radeon-hd-4670-review/4