Programaticly setting the value of a Select Query Property.

I have a query in which I'd like to use the username of the user currently logged in. The expression im using to retrieve the username is: Membership.GetUser().UserName.
Currently I have the following:
<asp:SqlDataSource ID="ProjectSource" runat="server" ConnectionString="<%$ ConnectionStrings:Code %>"
ProviderName="<%$ ConnectionStrings:Code.ProviderName %>" SelectCommand="Select Name, Namespace from Project where User = $Username">
<SelectParameters>
<asp:Parameter DefaultValue="" Name="$Username" />
</SelectParameters>
</asp:SqlDataSource>
<asp:GridView ID="GridView1" runat="server" DataSourceID="ProjectSource" />

I'd somehow like to set up $Username to be equivlent to Membership.GetUser().UserName.I'd be interested to hear of a better way, however, currently, I cheat. I stuff things like that when they authenticate to session variables (I only have 3 in my current project). Then I pull them in the sqldatasources from there.|||Yeah, my solution doesnt look to be much better. Currently Im Setting the default value every time I need to execute a query.