Gibs- Literally your comp is "dual core"- but today's "dual core" processors mean something slightly different
Allright you have 2 cores- but the purpose of using 2 cores in 1 processor instead of one is not to "HAVE 2 COREs" but to boost performance
How much L2 memory does those dual PIII have ? 256 or 512 for each processor.
New Core2 duo have 2mb or 4mb L2 cache to share for both cores.
Comparing 2 old processors made to work together with new dual core cpus is useless.
Completely different technology, different architecture etc.
Tuluain- 130 micrometers technology, Conroe- 65 micrometers
But apart from all that-
If you want to buy a (faster/dual core/other brand) CPU- Do not expect ANY other difference than (higher/lower) Frames Per Second and (better/worse) general performance (freezes, choppiness etc.) in ANY game !
CPU is just a kind of calculator which works on basic electrical signals- the only difference between CPUs is HOW FAST they can do calculations.