I am looking to build a new system. I am trying to decide which CPU to use for the specific tasks that I do on the computer. I know it's a beaten to death question in general, but I believe there is a proper tool (CPU) for the job. So here is what I usually do daily:
 
  * winxp pro
  * web design (photoshop, coding, running a server on local machine)
  * firefox with bazillion extensions :)
 
What I occasionally do:
 
  * music production (propellerheads reason, cubase, adobe audition)
  * watching movies
 
What I never do:
 
  * play games
  * video editing
 
 
So based on that, what CPU should I go with? Thanks!

Intel quad core would definitely fit your bill, but a dual core would also do.
 
Some thoughts:
 
Quad core: Q6600, Q9300 (release soon)
Dual core: E6850, E8400  

Price Range?
What parts do you need?  OS?  Monitor?  Mouse Keyboard?  
(Will presume all Computer Parts)

If you don't plan on overclocking or overclocking much Phenom 9500 is on sale at Newegg for 199.99.  Else the Q6600 is available for around $275.
 
If you want a budger build, I'd go with the AMD 5000+ BE.  A friend of mine just got his yesterday.  Upped it to 3ghz with no fanfare.  You might even want to consider a cheap opteron for what you're doing, but I know virtually nothing about them.

I am just debating on the CPU right now. Let's assume I have all the other parts. Budget just for CPU is anything below $500.
 
Quad seems like an overkill, since most apps that I stated dont even support multi core. I guess I could run servers and such on one CPU and apps on the other, that'd be good. Ah well, something to think about.

I don't really have a budget set, but I know that I don't want to go all the way to high end, but at the same time I don't want to cheap out on any of the parts and I am planning to build a good quality system. But I want to build it to my needs, that's why I don't want to go all the way to high end. So I think high-mid-range to low-high end is a good target. hehehe

$500 is a really large budget just for CPU.  The 5000+ BE is just 99 and will satisfy most of your needs.  Some of the older Conroes are good deals now too.  Some the older conroes should be getting pretty cheap now too.

I'd pick a quad. For example Q6600 does 9% better in Photoshop than a higher-clocked E6850, according to some review I read a long time ago.  
 
Either Phenom 9500 or Q6600, I'd say. The Phenom is cheaper. The Q6600 is faster and overclocks better. If you get the Q6600 also get a fast hard disk, or your fast CPU will just be waiting for the disk a lot of time. (I know mine does, and my WD5000AAKS is in fact a pretty good disk...)

Yeah sounds like Q6600 is actually a good option. I just checked and some peeps reported stable OC up to 3.7. So all in all, I think that is the decision

Thank you everyone for this awesomely fast participation and decision making process.

A nice raid controller card running raid 5 or something will solve that problem.  Allocate that $500 CPU budget to a controller card and some more hard drives.

 
May I suggest a RAID0 then? Having 2 of the same drives stripped makes a world of difference. Plus now you can get 2 500GB Seagate SATAII w/32MB cache for $119 each on newegg. I unfortunately got the 16MB cache ones but it still made a difference since I went from 8MB cache each drive to 16MB cache each drive.

 
ummm..
 
Q6600 $275, no question.  
This should have been a 1 reply post. The only way you would want something different is if you want to spend less money in which case get the slower AMD Phenom 9500

Everybody keeps telling you to get a quad core CPU...yet you have nothing that has any use for it!
 
Any cheap dual core is more than enough for you...and most people.
Get a CPU that runs close to 3Ghz stock and set the system up to run at that speed.
Games and most software are -still- rated on the old P4 scale.
 
 
The 5000+ BE (65nm 2X512KB L2) is onsale for $89 and a 6000+ (90nm 2X1MB L2) is $111.
 
Stock speeds are...the Q6600 is 2.4Ghz and about $150 more than a 6000+ that is 3Ghz,the 5000+BE is 2.6Ghz.

Yeah I gotta agree with ZOldDude.  I really don't see why you need a quad.  If you have the money to blow I say more power to you.  But seems like a waste to me.

 
Well, it depends. I do Web design too, and the things typically running there all the time are Visual Studio.Net, SQL Server, IIS, IE 7, FireFox. That's enough IMO to justify $275 for a quad as opposed to $100 for a dual-core. Of course, the OP's Web design might consist of a text editor, PHP and MySQL, and he'd be fine with a E2160. We need more info I guess.  
 
Also, music production software comes in lots of flavors, some smart enough to use 4 cores and some not. The OP needs to figure out what type he has, to make a good decision.

Most people do not have a bunch of different browsers open at the same time they are programming and running a server...and watching a movie...and playing a game while listing to music all at the same time.
 
If your a gamer then 2 cores are more than enough and the money saved is better spent on a high end GFX card...or a PC Power & Cooling PSU.

 
He said he often use Photoshop and other web design softwares, and they will likely (photoshop in particular) take advantage of mult-core. Aside from that, he also multi-task a lot (not keith's definition of multitasking), which may also benefit from the usage of multi-core. Also, he stated he has the budget of 500USD, which is more than enough for a Q6600. Therefore I recommended quad core over dual core.
 

 
3.0Ghz of 6000+ is not that much faster than a Q6600 at 2.4Ghz. You can compare clockspeed of the same architecture, but not different architectures. Core 2's architecture is roughly 10%~20% faster than K8 in IPC in most of the programs.
 
Taking Photoshop for example, an E6550, running at 2.33Ghz, performs relatively the same with 6000+, although having a nearly 700Mhz difference in clockspeed.
 

ZOldDude you forget that he is not much of a gamer. Plus getting a quad now will help himself future proof his system especially considering he can easily OC a Q6600 to 3GHz to match a 6000+ in brute speed and outperform it by much more.

Ahhh comeon... don't recommend the Q6600 to everyone... until... I get mine.

I just wanna be sure I get one before they run out.  

. o O (has those flash backs of taco bell... this item is only back for a limited time)