There's no hurry really. As far as I know, Scott has already picked up three or four different batches of memory, with no end in sight.
About the 3200 vs. 3700 question... that's really up to you. I believe Shadco has got his Twinmos 3200 above 210MHz with some good timings. I guess it depends on how much overclock you're aiming for. Since I run this machine 24/7, my regular memory and FSB speeds are lower than the maximum they'll do, but it helps me with overall stability a lot... and SETI doesn't mind that much
