Is the Corsair 450W PSU enough to power this system?

That PSU only has 1 PCIe connector. You'd have to use a molex to 6 pin PCIe adapter for the 2nd connector.

I would suggest switching to this OCZ 550w. It'll save a few $$, and has the needed connectors.
http://www.newegg.com/Product/Product.aspx?Item=N82E16817341022&Tpk=ocz%20550w

If you buy within the next 50 hours, you can get this Antec 620w for $40 with this promo code: EMCYWZP25
http://www.newegg.com/Product/Product.aspx?Item=N82E16817371031&nm_mc=EMC-IGNEFL081310&cm_mmc=EMC-IGNEFL081310-_-EMC-081310-Index-_-PowerSupplies-_-17371031-L02D