Dual-core just waits faster (Score 1)

Dual core processors might help, but with the exception of cost they are no better than multiple-cpu systems. Most systems are not cpu-bound, so they spend their idle time waiting on (1) you to make up your mind, (2) the internet, local net, or something that communicates via IP to actually deliver a packet, or (3) that put-lightning-to-sleep 7200 rmp ata drive.
Dual-core processors in most cases, like multiple CPU systems, simply wait faster for something to do. Spend your money on something really usefull - like a good book to read while you wait on your cable-modem.....