I live in Florida. My step father just passed away. I just found out he had a joint stock portfolio in my name and his girlfriends name as well (all 3 of us).

We liquidated everything and I just got a check for about $120k.

My stock broker said since our names were on the portfolio we don't have to pay an Inheritance tax, but do I need to pay regular income tax on this at the end of the year?

In the U.S. there is no federal tax on the inheritances. Your cost basis of the stocks you inherited is the fair market value of the stock on the date of death of your father. If the stock is sold at a price higher than your cost basis, you have a profit and must report on schedule D.
Read: Your U.S. Tax Return: Tax on Inheritances (http://taxipay.blogspot.com/2008/02/tax-on-inheritances.html)

I live in Florida. My step father just passed away. I just found out he had a joint stock portfolio in my name and his girlfriends name as well (all 3 of us).

We liquidated everything and I just got a check for about $120k.

My stock broker said since our names were on the portfolio we don't have to pay an Inheritance tax, but do I need to pay regular income tax on this at the end of the year?
Another question, he had about $40k in moneymarket and savings. Do I need to pay taxes on that as well or just the interest? Thank you.

If the portfolio was in your name before your step father passed away, then these stocks were a gift to you while he was still alive, and your cost basis would be the same cost basis as your step father had when he originally purchased the stocks (assuming the stocks have appreciated). If this is the case, then you report as capital gain the difference between the $120k and his original cost basis. You should check the exact ownership of the account - you say it was joint owned, but are you sure it wasn't owned by him with you and his GF listed as beneficiaries (i.e. payable on death)? Make sure you get this right - it could make a huge difference in the taxes you owe.

As for inheritance taxes - there is no federal inheritance tax, and no inheritance tax in the state of FL, so you're clear there. If any estate tax was due the executor is responsible for figuring that out and paying the tax out of the estate's assets before distributing assets to the heirs, so again you don't need to worry about that. Same for your question on the money market - no taxes are due from you, except that from now on with you will owe income taxes on the interest you receive.