Flowbe, dude...
OK stop for a second. I'm gonna _TRY_ and teach you something here. I can't take your lack or respect for the written word anymore. Hopefully I can do this without sounding like a total [censored] while still giving you the verbal [censored]-slap that you seriously need.
So let's look at where we've been shall we? Somewhere along the way you heard/read/got an email about Ettercap and said to yourself "Gee, that sounds cool. I want to play with that". So off to some search engine you went, typed in 'ettercap' and was presented with the place to find it. You promptly found the download page and proceeded to download the latest version.
How am I doing so far?
Now, unbeknownst to you, every single skill needed to get ettercap working has already been used by yourself. Yet, we had that tar archive ordeal yesterday, and now this little problem today. Now I'm not faulting you for not knowing what to do next. No one can know everything, and I for one know next to nothing about ettercap. I have never used it, or even tried to compile it. I'm just as ignorant as you are in this.
Continuing on (after the files are extracted, we don't need to repeat that do we?

), we now have a bunch of files on our harddrive that somehow we are suppposed to compl;ie into something we can run. Great, so htf do we do that?
We read the instructions.Wild concept, I know. As a quick little aside, in my computing experience, everthing I have ever downloaded has always come with _INSTRUCTIONS_. These documents almost always tell you what you need to know. These docs is where I got that info yesterday about ettercap not being distributed in binary format. I cannot stress it enough: READ THE DOCUMENTS!
So, let's assume you did all that and we still ended up where we are right now. [censored], why doesn't this crap compile?? At this point you have a couple options. Post a question here (what you did), or search the web for an answer (the better way to go). And seeing as how ettercap has its own site, the absolute best place to start searching is that site. A little bit of info that you can't really know without some experience is that forums such as this are not only a place to ask questions, but a place to find answers. Actually, I take that back, you have already realized this. Remember your question about good C books? didn't take you long to realize that you didn't need to ask that cause it had already been answered. Did you notice that the ettercap site has a forum? Seems to me that you would get far better info asking ettercap related questions there than here. And maybe, just maybe, this question has already been answered there
So I went over to the ettercap forums, and did a search for "windows compiling". No need to put ettercap in there, this whole forum is about nothing but

Now with a potential list of answers to our question we start reading threads.
after about 30 seconds, I find this:
http://ettercap.sourceforge.net/forum/viewtopic.php?t=2011&highlight=windows+com piling Read it. All of it. If you come back and ask a question that is answered in that thread don't ever expect my help again.
After browsing through that thread, it looks like the 0.6.9 and 0.6.b releases are windows only, and potentially the best ones for you. So, I went and downloaded it so I could READ THE DOCUMENTS inside and see what they have to say. Low and behold, one file inside the archive is called "README.WIN32". Hrm, this sounds promising. I quickly open it up for my viewing pleasure and what do I see...
COMPLETE INSTRUCTIONS FOR COMPILING ETTERCAP IN WINDOWS!!!I'd post em here, but they're kinda long, and I don't want to do everything for ya

But to briefly summarize, it looks like you have to do it in CGYWin. If you don't know what that is then bust out your favorite search engine and go find out.
So hopefully you get the point of all this. Just in case though, I'm going to spell it out. Everything you usually need to do anything is either included, or a couple clicks away. The ability to find the answer to your question is the single most important attribute you can possess if you want to ever do anything in the tech world. I'm not saying that you should never post questions here, or try and make conversation, but you need to realize the difference between good questions and stupid questions.
So if I do sound like a complete [censored] I apolgize. But you really need a kick in the [censored] here. Hopefully you can come away from this having learnt something: that it is possible for you to find answers to simple question fster than it is for you to post a questoins here.
infinite