It looks like there is not a very significant performance difference between
P4 systems using DDR memory compared to systems using RAMBUS memory, though
the choice of DDR chipset makes some difference with regard to this.  If you
go the DDR route, you have three chipsets to choose from among, Intel's
845-D, VIA's P4X266, and SiS's 645 chipsets.  I don't know enough about
these chipsets in terms of how they are working out for folks to say much
more than the Intel chipset is probably the most stable but slowest, while
the SiS chipset, since it supports PC2700 DDR SDRAM, looks to be the
fastest.

Hardware review sites, such as AnandTech will provide benchmark comparisons
of motherboards using these different chipsets, such as this SiS 645 chipset
review: http://www.anandtech.com/showdoc.html?i=1541&p=1

There's not much difference in price between high quality DDR memory and
RAMBUS, now.  This makes choosing between the two options even more
difficult.  However, it does look like motherboards using the DDR chipsets
for the P4 are less expensive than motherboards using the i850 chipset,
which supports RAMBUS.

John

              The NOSPIN Group is now offering Free PC Tech
                     support at our newest website:
                          http://freepctech.com