Cache User Details For The Duration Of Their Visit?

I've built a Repository that gets user details

Public Function GetUserByOpenID(ByVal openid As String) As User Implements IUserRepository.GetUserByOpenID
Dim user = (From u In dc.Users
Where u.OpenID = openid
Select u).FirstOrDefault
Return user
End Function

And I'd like to be able to pull those details down IF the user is logged in AND IF the cached data is null.

What is the best way to create a User object that contains all of the users details, and persist it across the entire site for the duration of their visit?

I Was trying this in my Global.asax, but I'm not really happy using Session variables. I'd rather have a single object with all the details inside.

Private Sub BaseGlobal_AcquireRequestState(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.AcquireRequestState
If Session("UserName") Is Nothing AndAlso User.Identity.IsAuthenticated Then
Dim repo As UrbanNow.Core.IUserRepository = New UrbanNow.Core.UserRepository
Dim _user As New UrbanNow.Core.User
_user = repo.GetUserByOpenID(User.Identity.Name)
Session("UserName") = _user.UserName()
Session("UserID") = _user.ID
End If
End Sub