Will my PSU be powerful enough?

I have a raidmax case with a stock 450 Watt PSU that came with it. Had a choice between that case and the antec with a 400 Watt, but the raidmax came with an lcd display. Anyways, I want to know whether or not my PSU will supply sufficent power for my components. Here is my future build.

ASUS A8N-SLI Premium mobo
AMD Athlon X2 3800
256 7800 GT
Western Digital 200 GB harddrive, possibly my old dell 80 GB as well.
2 x 1 G Kingston RAM
2 extra intake/exhaust fans on the case

Will my PSU supply enough power for me to run my computer safely. Or should I buy another PSU.

P.S I heard of a guy who bought a second PSU, drilled an opening and slapped a second PSU with which he attatched the power to other components. I think his CPU, Mobo where on one and the other components on another; however, I do not remember this very clearly and I am wondering if that is even possible.