Shador, I really feel for you. You might want to learn something from my own experience, when I was about your age and made some mistakes with regard to the JWs that I now sorely regret.
I was raised a JW, and most people in my extended family were JWs from back in the 1920s. When I was about 21 back in 1972, it dawned on me that something was rotten in Brooklyn, and I almost left. But I still lived with my parents, and they cajoled and threatened to kick me out until I gave in. I went back to square one, and "studied" again a couple of the basic "study" books from the late 1960s with a young brother a few years older than me. During the study, I really began to think hard about some of the doctrines, and realized that some of them were nonsense. But because I had no job skills whatsoever, and could only see myself living in extremely unpleasant circumstances if I were on my own, I bit the bullet, yielded to the pressure, got back actively in congregation activities, and went on with normal JW life. I now realize that this was the biggest mistake I ever made.
When 1975 passed without Armageddon coming, I gradually got uneasy, and could not keep from imagining what my life would be like in another 20-30 years when Armageddon still hadn't come. By that time I was married and really starting to think about future in terms of supporting kids and so forth. In 1978 I went to college, found out that the Society is an extremely dishonest organization, and became inactive. Except for a short stint after graduating, I never was an active JW again.
When I think back to the wasted years, it really pisses me off. I wish I had been brave enough to leave home at 21, and take whatever came along. It would have been good for me in the long run, I'm convinced.
Today, out of the JWs for nearly 30 years, I have a good job and am respected in my field. You're obviously bright enough, and already have enough good job skills, that you'll do just fine when you end up on your own.
Don't make the mistake I did, and cave in. You'll sorely regret it in the long run because, knowing what you know, you won't be able to live with the constant barrage of bullshit the JWs will shove your way. Until the early 1990s I still attended the occasional meeting or assembly because of my JW wife (we divorced in 1994), but found it almost impossible to refrain from jumping up and shouting, "What the hell is wrong with you people? Can't you see the bullshit they're shoving down your throats?" I finally got to the point where I was physically ill by the end of a Sunday meeting, and then I quit going altogether.
As for ammunition to use to show your parents how ridiculous the JW religion is, several posters have correctly pointed out that the Fundamental Doctrine of Jehovah's Witnesses amounts to worship of the Governing Body. These codgers have truly put themselves in the place of God in the minds of most JWs. This is easily proved: tell a typical JW that you've lost faith in God and they'll be a little bothered, but them him that you've lost faith in the GB and they'll be a lot bothered, and call you an apostate.
A related claim is that elders -- and GB members in particular -- are appointed by holy spirit. The falsity of this claim is easily demonstrated: God would not appoint a child molester to the position of elder, much less a GB member. However, former GB member Leo Greenlees was a homosexual and molester of boys for decades. But he was invited to become a Brooklyn Bethel official around 1964, and was appointed a GB member around 1971, and booted off the GB in 1984 after the parents of a 10-year-old boy brought charges against him of molesting their son. The rest of the GB found Greenlees repentant, and sent him off as a Special Pioneer. Greenlees died around 1989, a respected member of a New Orleans congregation. This is absolute proof that the JW Governing Body has nothing to do with God. Anyone who doubts that what I've said is true can simply call the Watchtower Society's main phone number in Brooklyn, and ask to speak to someone in authority about what happened with Leo Greenlees. Assuming the operator forwards the call to someone in authority, the caller will simply be told that the Society does not discuss the situation. Here is the key point: the WT spokesman will not deny what happened with Greenlees, because the Society does not want to be caught on tape lying about it.
Another impossible point for JWs to counter is to use Luke 21:8 against them. This passage essentially states that anyone who comes in Jesus' name and claims that "the kingdom is at hand" should be avoided. JW leaders certainly come in Jesus' and Jehovah's names, claiming to be their spokesmen. They certainly today, and have often claimed that "the kingdom is at hand". Publication titles include God's Kingdom of a Thousand Years Has Approached (1973), The Approaching Peace of a Thousand Years (1969), The Kingdom Is At Hand (1944) and The Time Is At Hand (1891). Because JW leaders fufill both parts of Jesus' warning in Luke 21:8, they should not be followed by true Christians.
If you use this argument, likely you'll get a response something like, "Luke 21:8 can't apply to us because we're God's people!" I got this when challenging GB member Albert Schroeder 12 years ago, and other critics have gotten the same "answer". But this is entirely self-serving and ignores the fact that the passage does not allow for exceptions.
You can get all sorts of good information from this website and others. Continue to use your brain and accumulate information. Do whatever you need to get out from under your parents' thumb, or you'll regret it. That they've taken away your own property (your PC) when you're their very means of financial support speaks volumes about how they view you -- not as a competent, reasoning adult, but as a child needing to be controlled. You don't need this, and you don't have to live with it.
For a lot more information about JW dishonesty, visit this website: http://corior.blogspot.com/ . Take advantage of what many posters tell you. Begin to live life!