This is my no-brainer's guide on which CPU type is the best for you (YAY!) Anyways, first off, ANYTHING and I mean ANYTHING is better than a single-core processor. It doesn't take a genius to know that 2 brains are better than 1 and is the same in the case of single-core vs. dual-core. Sooooo, if you're still utilizing a single-core processor then there must be a hardcore reason why you are using a single-core (no offense to those that still use one.) So, single-core < dual-core...CHECK!
Now, things start getting interesting here because we are in multiple-core processors in this section. Dual cores are the best for price per performance but that is IF you aren't doing any hardcore 3D renderings, Photoshop editing, video rendering/editing, massive WinRAR compressions, etc. Basically anything that deals with heavy CPU calculations. Both Intel and AMD have dual core processors but Intel's venerable Core 2 Duo series beats down AMD's Athlon X2 series of CPUs. Nonetheless, AMD offers better pricing for the performance than Intel's Core 2 Duo series. However, I'm getting off-point and I really should say that dual core CPUs are perfect for games because even today's PC games don't use more than 2 cores (I've only heard rumors of a few games actually utilizing a quad-core fully but again, those are rumors.)
A tri-core is unique because AMD is the only one who provides these CPUs (I guess Intel thought the masses would see an odd # of cores on a processor as useless) and the story behind these tri-cores are rather special. When tri-cores first came out, they came out on the Phenom X series (1st generation Phenoms to be exact) and were sold as Phenom X3s. The reason behind this is because AMD, rather than throwing out CPUs with a minor defect, decided to save them and sell them in a different product line (pretty smart marketing IMO) and this, in turn, gave birth to a unique line of CPUs for AMD. Yes, that is right, faulty Phenom X4s (even today's Phenom II X4s) were sold as tri-core CPUs. The faulty ones had 1 defective core so, as stated before, instead of throwing them in the garbage, they disabled the faulty core and the cache that was with the core. The Phenom II X3s are pretty much the sweet spot in terms of multi-core performance per cost. You have 2 cores that are perfect for gaming while a 3rd core is on reserve for extra duty. And for rendering, a tri-core can do it MUCH better than a dual core because of that extra core. For a budget gaming system, my CPU recommendation is the Phenom II X3 720 black-edition CPU. So, single-core < dual-core < tri-core....CHECK!
We are living in a world where quad-core based systems are starting to become the trend with PC enthusiasts. Intel and AMD both have a massive line of quad-core processors on the market right now while dual-cores are being outdone but are still in existence. AMD's quad core lines consist of the Athlon II X4s and the Phenom II X4s (plus the older Phenom X4 line) while Intel's line consists of the Core i5 750, Core i7 on both the LGA 1156 & 1366 platforms and their older Core 2 Quad (both Core 2 Duo and Core 2 Quads are reaching the end of their life cycle) line. Within these lines are CPUs with different clock speeds and different cache sizes. Both lines have been contending with each other like 2 boxers in a boxing ring and all I can say is this: for the price/performance, AMD is the way to go. For pure performance regardless of price, Intel. When it comes to raw performance, Intel tops AMD by a large margin but AMD provides incredible competition with their gracious pricing. Quad core CPUs are pretty much the cream of the crop, I should say because they offer great performance in just about everything. But they do fall in performance when it comes to games because most games aren't optimized to fully use all 4 cores and to make a quad core CPU truly shine, it's recommended to use a 64-bit operating system. But when it comes to 3D rendering, Photoshop work, video editing/rendering, complex engineering programs, and so forth, a quad-core is what you really want. You have available to you, 4 cores all running at the described clock speed thus making complex calculations done in a matter of minutes. Quad cores are, however, pretty expensive (although the cheapest quad core processor out is at only $99.99) but those quad-cores are the higher end quad cores. So, single-core < dual-core < tri-core < quad-core....CHECK!
Now you're probably wondering, are there any CPUs out there that have more than 4 cores? SURE THERE ARE! We live in a world where CPU technology is getting smaller and smaller (current size is 32nm) and that's small enough to create 6-core CPUs. AMD has a 6-core Opteron CPU but those are strictly for business server uses. You can use them if you want but it's not recommended for the average consumer. Intel recently launched the much talked about Gulftown CPU: Intel Core i7 980X. This is their most extreme CPU to date and features a 6-core CPU running at 3.33ghz with a whopping 12MB L3 cache + an unlocked multiplier for easier overclocking + Hyper-threading (giving you 12 processing threads in total in Windows Task Manager!) Pretty insane CPU with a pretty insane price tag....of $1,100. But then again, this CPU is really for those with DEEP ASS pockets and are heavy enthusiasts who need that kind of raw power. AMD will release a consumer level 6-core CPU later this year.
So, if you are a gamer who wants a pretty badass system but don't want to spend a fortune on it, then a tri-core is what I recommend. It has more power than a dual core in terms of processor-heavy tasks and yet you aren't wasting 2 extra cores and you save some more money to sink into something more important like a bigger graphics card, blu-ray drive, secondary hard drive, better CPU cooler, whatever you need/want. I hope this helps you readers out a bit. Thanks for taking the time to read this and happy gaming!