google and wikipedia are very useful resources for your questions and most of all just spending some time sorting through peoples opinions on forums along with reading news articles on reputable web sites.
The simple answer is you don't care about cache, and as for speed, more is better.
cores, are a different story, for gaming (until very recently) 2 fast cores were better than 4 slower cores, but now games are preferring 4 cores more often, and you can easily buy 4 fast cores now a days.
The anand bench above is really useful. And are the only way to understand if X is better than Y.
take Cache, cache has been used in the past to cover for slower processors, but if the processor is fast enough then it doesn't matter as much, everything today comes with enough cache. the analogy here is buying car based on the size of the pipe from the fuel tank to the engine, you don't need to know these days.
take clock speed, you cannot compare two processors from different families by looking at clock speed, the amount of work per cycle that each processor can do is different and therefore it is Ghz vs Ghz is not appropriate. AMD's latest chips for instance have a different architecture than intels, in such a way as to take longer over each instruction and need more cycles to do an amount of work. the analogy here is buying a car based on how fast the engine can rev to, its not that relevant as gearing transfers that to the road (its not a brilliant analogy)
hyper threading, is taking one real core, and making is pretend that it is two cores, its about 80% effective in some cases, less so in others. the analogy here is buying a car based on the number of cylinders alone
All of the cars in the above analogy will get you from A to B in whatever style you want (quickly, wth family, with tree in the back) as they are all designed to do all things. A server chip, xeons etc. will do the same, but with a nicer leather interior.
But what choice really comes down to, always, is what do you want to pay, want can you afford for the whole system, because when it comes to gaming the cpu is about equal to the gpu, if not a little less important.
My personal choice would be at the moment, a true quad, and probably an i5-2500K, because its not much more than the lower i5's, and you can make is faster if you need/want to. The i7 is not needed for gaming. Latest AMD's are not very good at the moment, the previous amd's are weaker than the i5, but thats if you can afford it.
thanks 13thmonkey and everyone else! I will be looking at those bench marks.
Um... budget is to buld basic desktop (my 6yr old compaq machine is pretty much gone - so i've decided to get a new pc but by building up my own.), im going for a AMD Athlon II X4 631 2.6GHz with a cheap mobo that supports. again cheap hard drive and ram and cheap graphics. cheap cheap and yes, more cheap.
*also guys, today a friend of my bought a CPU fan cooler. it was a Arctic Cooling Freezer 7 Pro rev 2 - for some reason when his mobo kept saying CPU fan error, it was connected in the correct fan header (and it did work because stock cooler was ok). Its was a AMD board, what mobo i dont know but can find out and inform you wonderful people !
Make sure your mobo is am3+ or whatever their socket name is so that should you fall into a little cash you can upgrade to the highest CPU's that they do.
The alternative is a sandybridge pentium socket 1155, again you'll be able to upgrade to highest intel 1155 should you find the funds.
Generally the amd options are seen as being better at the value end of the market.