In regards to actual brand names, most high performance modules are the same. Only differences matter when really overclocking the modules.
Go for the best price for timings and speed. IMO, read reviews on Newegg or something to see the reliability of the RAM in question. (I've had a friend who bought some Corsair RAM; most ratings on Newegg complained of defective modules, and what do you know, my friend's modules failed on him...)
I would usually go for the lowest voltage if possible - it will run cooler, likely more stable, and put less stress on the memory controller. You can get DDR2-1066 at 1.8 volts now, which is the way to go if possible.