Avoiding duplicate entries

I am creating a list of companies that I want to contact and have created a User Form that allows me to enter data. However I want to avoid entering the same company twice.

Is there a way of checking the name entered in the first box so that if the name exists, all the known info for that company name is displayed. I am then given the choice of adding a different company (same name but different address) or adding a completely different company.

My VBA skills are non-existant, what I have done so far has been based on examples found on the net

TIA

Dom

I really don't have a clue where to start so for the time being I start every data entry session by sorting and then printing a pdf of the current data and having that open on another screen.

Steve