ASP Help

I am trying to but together something of a portal. It?s going to have an e-mail checker, News, Calendar, Task list, Address book, Important Links, Downloads, Message Board, Item list lookup, and Item list add/edit. Each of these I can develop separately on my own. My problem is in developing the user name and password system so that the people logging in only have to login once and that can say hey Greg just logged in and shows him just his e-mail, address book, task list, and Calendar and no one else?s.