I see it as the Circle of Life (Lion King ftw!). I'm an omnivore, so I eat everything. What's more; our bodies are made for eating meat and plants, int hat we need certain amino acids from both parties to survive.
If you go through with it, well, that's up to you. Also depends how much you will be? Only fish/chicken or no meat at all? What about eggs, milk and such? In the end, you need to remember that you need a balanced diet with a lot of tofu, beans and such to give you the nutrients that meat is usually the sole supplier of. And if you do enjoy the occasional piece of meat, why restrict yourself? Eat what you like. I have salad-weeks myself where I'm pretty much a vegetarian and others where I eat half a cow in 48 hours.