Once you've logged in, go to http://developer.apple.com/iphone/index.action and you'll see the links on the right side-bar under "iPhone Developer Program". They don't show unless you're logged in. If you don't see them after logging in maybe the servers haven't updated your account or something...
This is happening to me, I have paid, got my activation code and activated but still get Access denied on the beta areas. How did you overcome this problem?