You have the right thinking- limit yourself x amount of time. BUT make sure the computer is turned off so you aren't as tempted.
Plan it out. You can't just make goals spurr of the moment and accomplish them. Make a plan. On Monday, I Tama_gal_3 will only one hour on the computer. Tell your family and your friends so they can help get you pumped up and encouraged. Next, decide if you are going to limit it more. Take of five or ten minutes every week. Last but not least, set a reward! Do you have a favorite kind of icecream or candybar? If you follow your plan for two weeks, you can have some of your favorite treats.
Stick to it. I live on the computer, too, but planning it out is something you just have to do if you want to accomplish your goal, no matter how small. ;]