Word Count Question: WTF?

So, I usually read up on blogs and sites about the word count of novels. There are a lot of people who pretty much don't know what the hell they are talking about. They may know a person in the publishing business, then write a stern, smart blog trying to strut their stuff. I was just recently reading one where it says that Microsoft Word can be errorneous with the word count by about 20000 words depending on spacing and font. Um... excuse me, but one word in Word is going to be counted on the bottom right corner as 1 word. I'm currently writing in Times New Roman; sometimes I double space the entire thing, sometimes I leave it single spaced because I prefer the look (I know, it's neurotic, but bare with me); I'll be editing it double spaced of course. So apparently Times New Roman tells a person their word count is 20000 words above what it really is and that to change the font size to 12, make it courier new and double space it will give a person the correct word count. Well, I tried this and there is no difference in the word count. I am currently at 59000 words and expecting the novel to come out around 75000- 80000 once I am done with it. Please, someone who knows what they are talking about, preferrably someone who is in the publishing business or has been published. If this strange thing is true, can someone give me a calculation to find out my actual word count: say my novel is size 11 font, Times New Roman, single spaced, justified. Thanks.