Aadam,
You will want to use the ArrayList class in the System.Collections
namespace. It will allow you to access items in the order you add them.
If you need the ability to look up a value using a key, then use the
Hashtable class in the System.Collections namespace.
In .NET 2.0, you should use the List<T> and the Dictionary<K, V> types
respectively (they are generic, with T, K, and V being type parameters).
Hope this helps.