I know what you're refering to. How many deductions do you have on your W-2's? If you're single, rent and have no dependents, then you only need one. i found that having two deductions on mine made me owe so much money, despite hovering below poverty level. If you're not sure what to do, talk to your HR rep at work. I don't remember what all the deduction reasons are, but I cut mine back to one deduction. Because no one can claim me as a dependent. I had checked another one on one of my W-2's... thinking it made sense to me. yeah... I was in for a shock. I changed it immediately.
i don't know about if you own your home, or are married or have kids... since I've never been in any of those circumstances. But talk to your HR rep.
You can't change what you now owe, but you can change your 2006 W-2 status ASAP. As for what you owe, you don't have to send them all of it. Send them what you can, say $50, if you can swing it. They'll eventually send you a bill... you just keep sending them a little bit whenever possible. I know... it's maddening.