vb.net collection - data type question - newbie

I am converting a vb6 application.

In it I use a collection of classes with the index being the number, in order that the class was added.

like

mycollection.add myclass, "1"

so I can loop through

for i = 0 to mycollection.count
   myclass.item(cstr(i))
next

Is there a better data type to use?

I don't remember why I used them in the first place, it could have been because there was no hash type.