>C# I'm afraid. Also assuming you want the same functionality as VFP with Flags=1:

public string StrTranInsensitive(string searchIn, string searchFor, string replace)
>        {
>            string result = searchIn;
>            int i = searchIn.ToLower().IndexOf(searchFor.ToLower());
>            if (i > 0)
>            { 
>                result = searchIn.Substring(0, i) + replace + searchIn.Substring(i + searchFor.Length);
>            }
>            return result;
>        }

Not really stress tested - may fall over easily but should be a starting point.....

Thanks