Upgrade

/// <summary>
/// Converts a hashtable to a generic ditionary
/// </summary>
/// <typeparam name="TKey">The type of the key in the hashtable</typeparam>
/// <typeparam name="TValue">The type of the object in the hashtable</typeparam>
/// <param name="t">The hashtable</param>
/// <returns></returns>
public static Dictionary<TKey, TValue> Upgrade<TKey, TValue>(this Hashtable t)
{
    var dic = new Dictionary<TKey, TValue>();

    foreach (DictionaryEntry entry in t)
    {
        dic.Add((TKey)entry.Key, (TValue)entry.Value);
    }

    return dic;
}

Hashtable t1 = new Hashtable();
 t1.Add("pi", Math.PI);
 t1.Add("e", Math.E);

 var col = t1.Upgrade<string, double>();