I do plan on upgrading to a dx10 card but i dont know how soon. So 600 watts is the minimum to run the current DX10 cards, and most likely the ATI's when they come out , and 700 watts for sli or crossfire ?
No, only if you think you'd buy the highest end cards and SLI them, would you need anywhere near 600W, not 700W.
However, you're not getting true wattage with that PSU, you're getting $85 dollars worth. Welcome to the PSU games, ratings are just paper specs that depend on the rating system used, in the end the actual components necessary to support any given wattage and a reasonable lifespan, still don't vary by much.
Keep in mind that your Raidmax 450 is not a typical 450W PSU, most major brand 450W PSU would run a midgrade system and midgrade DX10 video card. Even so, better to have a PSU with more reserve current than you need, than too little. In worst case, you have a PSU more capable of handling the NEXT upgrade after the one currently planned.
The bottom line- factor for the specific parts, not a generalization like DX10. Specific CPU, # of hard drives, and specific video card. Some DX10 parts will even consume less power due to smaller process size, but to pick a wattage you'd have to nail down exact parts powered, else overbuy.