I'd recommend losing the high-end 3D card. It will be throttled by the slow CPU and the 2x AGP bus on your motherboard. You can get an AGP card that will work just fine for $20 (or less) or so if you shop around.
In fact, here's one for $19.99 at New Egg.
If you lose the high-end video card, an Opus 150w would do the job easily and leave you room for expansion or upgrading.