Yes, C5Pro will use your dual processor PC. Actually, clock-for-clock, the old P3 is better than a P4 at rendering. You might be able to match a single P4 based PC with a 1.4 GHz CPU? The Intel "M" series CPUs are based on the "old" P3 architecture. The Centrino has a higher Instruction Per Clock than either the Pentium 4 or Athlon XP.

Be interesting...maybe you could post some rendering results?