if you use an intel system, then you want intel chipsets (via will just mess it up). On AMD system, you can get away most times with VIA chipsets.
SiS chipset though slower, is still quite good and would easily be in the run for contenders in the mobo business.
What exactly you want to do with your system will depend on how much RAM you really need.
RDRAM is still the best choice for Intel chipsets, but never go for SDRAM (you will cry about it in the future *near future lol) for the new systems. DDR 266 is different from DDR 333, so if you go with 256DDR RAM, make sure you are getting what you want:
DDR266=PC2100
DDR333=PC2600, or is it PC2400 lol (sorry I forget which one now, but I think it is the 2600).
Judging that you like to use CoolEdit, I would suggest you try buying 2 sticks of 256MB DDR RAM or one stick of 512MB DDR RAM (in the long run you will appreciate it better).
Also what OS system you plan on running?
-if win9x then 256 will do you fine, but on win2k and especially XP you will want more--the more you handle bigger files and encodings.
256 is good starting point for those systems, but always get as much RAM as you can.
Good luck