>I'm using SQL Server Authentication, with the account SA and the password 'password'.
>
>At the moment I'm trying to determine that ports 1433 and 1434 (UDP) are open, which I believe they are. I have also installed SQL Server Managment on PC01, and I'm attempting to connect to the SQLExpress on PC02 but that doesn't work.

Being SQL Express, I'm assuming it installed with a default instance name of SQLExpress. Are you using that name in your connection string?