In my main application, Conroe performance is very poor. Slower
than my really old A64 3200+. But in everything else, Conroe is
faster. I have the machine pretty well tuned and I seldom see
lag of any kind on the machine.
If you're doing some really disk-intensive stuff, though, I can
see disk performance as an issue. One potential solution is to
employ a ton of memory so that your applications can take
advantage of buffering and, perhaps, block disk reads and writes.
x64 may provide an advantage in this area.