Insert id

 For SQL Server 2005+, if there is no insert trigger, then change the insert statement (all one line, split for clarity here) to this

INSERT INTO aspnet_GameProfiles(UserId,GameId)
OUTPUT INSERTED.ID
VALUES(@UserId, @GameId)

For SQL Server 2000, or if there is an insert trigger:

INSERT INTO aspnet_GameProfiles(UserId,GameId) 
VALUES(@UserId, @GameId);
SELECT SCOPE_IDENTITY()

And then

 Int32 newId = (Int32) myCommand.ExecuteScalar();