This is long but worth it if you want good and bad about Dual Processors.
Dual CPUs are powerful and are very good for servers, 3D rendering, and music compiling, HOWEVER you MUST have a operating system that supports dual processors (Windows Server, 2000 & XP Pro also Linux) and the program itself MUST also supports dual CPUs. There are a lot software that support and actually use the advantages of dual processors, i.e. Pro/E, Adobe Illustrator. When it is working properly with the correct programs it is ultra fast. My Dual PIII computer can render a 10meg file in Pro/E just as fast as my P4 3.06 w/HT. And the PIII is three years old.
Games do NOT only the way you would think on a dual processor system!!! It only uses one processor!!!
Also it is NOT like having two computers side by side. The speed is still the same, it just can do stuff in parallel instead of linear. You are restricted to the speed of the harddrive, memory and video card. Also if you render something and play a game at the same time is not practical because the game is going to the first CPU only and the rendering already using that processor.
I have a Dual PIII – 1.0Ghz that I use for my server with Windows 2000. It is powerful, but it is not a gaming system. I use to model components and assemblies in Pro/E, now it is just my file and gaming server.
Plus it is very expensive. The motherboards are about twice the price, and then you have twice the price of the processors (you have to go with a PI, P-Pro, PII, PIII or Zeon, because you can not dual a P4 chip and I don't know if you can dual an AMD chip at the time I setup my dual system you couldn't) and then you need a harddrive that is going to system dual processes. That would be something in the SCSI world, like Ultra2, Ultra160 or Ultra320 SCSI.
If you want something that is powerful cost is go and that uses dual processes without any special program, then get a P4 w/HT. HT = Hyper-Thread technology and it is one physical CPU but has twp logical processor built in. I have a P4 – 3.06 w/HT, running Windows XP Pro (only need standard XP to use HT) and I love it. I can burn a music CD and play Unreal Tournament 2004 at the same time and not miss a beat. Use the ALT-TAB and go in and out of Unreal to my burning software without bogging down my system. This HT thing is some good stuff.
Bottom line, unless you are running a server, rendering movies, making movies graphically in 3D, modeling and analyzing in Pro/E or similar program…it is NOT worth it.