The 2800+ doesn't even come close to comparing with the 2.8c chip... nor the 2.6c... nor the 2.4c... well it might win a benchie or two against the 2.4c but overall it looses.
Also you don't want the P4C800 you want the P4P800 which costs significantly less for the same performance.
So P4 2.4c - $172 (You want a c varient chip on any of the new canterwood/springdale chipsets. 2.6c $215, 2.8c $265, 3.0c $397, 3.2c $714)
Asus P4P800 Deluxe - $142.00 (There are cheaper versions, but this one has a good set of features.)
Corsair 2xCMX256A-3200C2 (512mb Total) - $126 (This is the recommend ram by corsair, about 63$/chip.)
Total: $440
ASUS A7N8X Deluxe 400Mhz Support - $124.00 (Deluxe 2 Deluxe)
AXP 2800 333MHz FSB - $166.00 (The cheapest 400fsb chip is the 3000+ at $294, the 3200+ costs $439. The 3000 compares closest to the 2.6c and the 3200 closest to the 2.8c)
Corsair 2xCMX256A-3200C2 (512mb Total) - $126
Total: $416.00
Performance wise, the intel high end platform is dominating the amd platform. Lower middle range is still amd's market because their prices can't be beaten. The AMD PR rating is just way way off compared to the 800mhz fsb intels... like 400-800mhz off.
As far as ram goes, Kingston, Geil, Mushkin!, and Corsair are all good choices so long as you avoid the "value" ones. I like the Corsair personally but they all work very well.
Shadus