The P4B266 is nice. Intel always makes solid chipsets, you know?
The other alternative is the P4S333 with the SiS645 chipset. Good reports all aound on this chipset and the mobo in particular. One big advantage with this one is it has the appropriate dividers and what not for the 533MHz FSB P4's already. AFAIK the P4B does not (though maybe a new BIOS could change that?) so ith the P4S you will have a solid upgrade path (or use a 1.6A or 1.8A and have the 533 FSB today! )