im thinking 2x256 for dc ddr, or should I just go with 1x 512 for now and try to get another 512 later?
well, if you are expecting to be getting more memory later, i would go with a single 512MB DIMM. there are advantages to getting 2 modules, especially for troubleshooting purposes. but then again, it;s best not to take up memory slot spaces with small increments if you are planning to get more sometime soon. and if you are planning on OCing, a single DIMM places less load on the memory conroller.
will I notice a big difference between just regular pc2700 , or dc 2700?
i don;t know for sure. if history proves to be the rule, probably not at first (aside from maybe benchmark scores). the rest of the hardware/software industry will need to play "catch-up" first. i think there are some other folks around here who can fill you in better than i on this.
One other thing, I was told herei n the past that win98 does not manage more than 384 mb of memory well
with xp pro, can it handle 1 gig reliably?
win9x did have a hard time managing more than (if i recall) 512MB of memory. there were tweaks to help this, but if you have winXP as an option, the question is yes..... XP will manage 1GB just fine.