Re: INTEL P4 3.0 GHZ or AMD 64 2800+????
The way I see it always go for the best mobo out there, and that way you'll have compatability for longer and will save you money in the long term not having to upgrade so often. I'd go with the AMD out of what you proposed hands down.
However I'd get the best mobo with a 939 socket and then the winchester cpu. Best mobo, best cpu, top quality ram. The rest is ever changing so buy budget to get it up and running if needs be (ebay or something) and then as you get more money upgrade the rest.