Req'd Est. tax payments 99,00,01

[Guest lbspete]

I rolled 80k from a 401k to a IRA and then coverted to a Roth in 1998. This increases my income by 20k/year for '98,99,00,01. ok so far. For '98 without the conversion, my tax liability was ~10k. With the conversion, my tax liability increases to ~15600 (10k+(20k*28%)(I'm in the 28% tax bracket). Three courses of action I think; 1) Do I now have to change my witholding to make sure that at least 15600 is withheld instead of at least 10k, or 2)do I have to make estimated tax payments to make up the difference between 10k and 15600, or 3)make sure that at least 10k is withheld and then make a big payment to Uncle Sam on 4/15/00, 4/15/01, & 4/15/02?

Thanks for your help!