No. I won't really make any particular recommendation, but I will disabuse you of a few erroneous beliefs you hold.
Dual CPUs and dual core, first off, are two entirely different things. They should not be confused. Dual core is a much lesser version of dual CPUs, which is cheaper because a lot of the circuitry is shared between the cores. Of course this is also why it's a lesser version. Only one core can read/write data from/to the rest of the system at a time, as opposed to two independent operations happening simultaneously with dual CPU.
Secondly, if you have 2x500MHz CPUs that does NOT make for the equivalent of a single 1GHz CPU. On multi-CPU and multi-core systems, clock speeds do not stack. It means each core, or CPU if the case of SMP, is operating at a specific clock frequency. Each core, or CPU, is operating independently of the other(s). Multi-core CPUs are not quite as independent as multi-CPU, but each core is effectively treated like a separate CPU by the software. The logic on the CPU itself will attempt to sort everything out, but it's not always going to be perfect, and sometimes you'll have one core blocking the I/O of another core, or cores.
Third, any system sold for under $1,000 is not going to be powerful. Maybe by the standards of what you're using now, but the quality will suffer at those price points. All those bells and whistles cost money to produce, so the more of them you cram into a system at a low price point, the more SOMETHING else had to give. Usually that's quality control, since tech support was an early casualty in the price wars. They also got rid of printed manuals, restore media, etc, so all that's really left is the quality of the components that goes into the system. Say what you will about Apple systems, but their build quality is heads and shoulders above anything else I've seen, and when you call for tech support in the US, you get someone in the US, who speaks english fluently, sans any heavy accents that are difficult to filter if you're unaccustomed. Pretty sure it's a similar case in other countries.
By and large, Apple is the only company out there selling multi-processor systems that I'm aware of, outside of special server builds. Of course if you meant multi-core, then those are a dime a dozen. It's pretty much impossible to find a system that ISN'T multi-core. Even your bargain basement netbooks tend to have multi-core CPUs. Even smartphones are getting multi-core CPUs now.
I'm shopping for a new, powerful PC for both artist work and gaming. (And no, I don't need or want a Mac.) My old eMachine has a Pentium (4) 3.06ghz processor. Isn't it true that the new dual core processors that say 2.93ghz are equivalent to almost 5ghz in speed?
I'm fairly computer literate and I know what L3 cache is, as well as Double-Data-Rate3, and want a new comp with a multi-processor.
I'm prepared to spend $900+. What are the best options in that price range? I'll be using Photoshop and 3dMax. What's the best buy for the money and my needs?
While I don't probably need a comp with a quad-core processor, out of curiosity, is there a comp with quad-core processor for under $1,000 out there? Thanks for any forthcoming help to my questions.