What's a CAT6 cable for?

Did anyone here sign up for Screamyx's 4mb broadband promo? I heard it's way faster than what we are getting now. Though i'm having the 1mb package, i have a feeling i am not getting the full 1mb speed i'm paying for. I may need to have a few more pcs running concurrently, so a fast line is definitely a must for me. There's gonna be another pc fair. Hope i get a good deal there. Now i have this CAT6 cable and have no idea why i bought it. I'll just leave it in its box and hopefully, use it one day.