The NV20 will be announced at the end of February. I expect availability to be at the end of March with a cost of $500. A couple of months later (May/June) it will fall to $400. I am just guessing, but an Ultra will probably cost $300, a Pro $200, and a GTS $100-$150 depending on the features. An MX will probably cost $70-$100.
The Radeon2 probably will be anounced late spring and arrive around June. From xbitlabs.com:
<< R200. This 0.15 micron chip belongs to the next generation after Radeon. The chip will have 4 rendering pipelines and will work at 300MHz. It will support Dual Display and T&L. the first samples should be available in February 2001, while the mass production starts only in June 2001. >>
The real problem that I see is that to justify the prices of these cards, some serious software needs to be released. Running Quake 3 at 1600x1200x32 @ ever higher fps is worthless. The games need to look more realistic to justify the cost.
As for a system to build, wait until the DDR motherboards come out and pair it with a Thunderbird. DDR/Rambus with a P3 makes no sense due to bandwidth constraints on the CPU. The P4 is too expensive compared to Thunderbird.