All modern video card's are now FULLY optimised for 3DNow!
A V3 will be peaked out with your system. More powerful video cards will not give much more improvement if any, except for 32bit. The V3 is limited to 16bit. Some 3d games now being released will only work if your 3d card supports 32bit. A V3 in those games means you must use software mode. I am in that situation now. Another factor to consider besides 32bit 3d is the future. As I said, the V3 is maxed out with your system. Keeping the V3, and upgrading to a 1Ghz system will not give you much of a performance boost, if any.
At least if you get a more modern 32bit card than the V3, you will have just as good 3d performance, be able to run 32bit games, and when you upgrade the CPU in the future, the video card should scale nicely, and you will see a huge performance boost. Plus, other compaines are still in business....