You can upgrade the SQL Server standard to SQL server enterprise edition
Steps from boks online:-
How to perform an edition upgrade within SQL Server 2000 (Setup)
To upgrade a SQL Server 2000 installation to a different edition of SQL
1.. Insert the MicrosoftSQL Server 2000T compact disc for the edition
you want to install into your CD-ROM drive. If the compact disc does not
autorun, double-click Autorun.exe in the root directory of the compact disc.
2.. Select SQL Server 2000 Components, select Install Database Server, and
then setup prepares the SQL Server Installation Wizard. At the Welcome
screen, click Next.
3.. In Computer Name dialog box, select Local Computer or Remote computer.
4.. In the Installation Selection dialog box, click Upgrade, Remove, or
Add Components to an existing instance of SQL Server, and then click Next.
5.. In the Instance Name dialog box, click Next.
6.. In the Existing Installation dialog box, click Upgrade your existing
installation, and then click Next.
7.. If Setup detects that you are doing an edition upgrade, the Upgrade
dialog box appears. Click Yes, Upgrade my< to
upgrade the feature set of your current installation, and click Next.
8.. After the upgrade is completed, you are prompted as to whether you
want to install additional components. If you click Yes, the Select
Components dialog box appears. Accept the defaults or select the additional
components you want to install, and then click Next.
You can select an item in the Components list, and then select items from
the related Sub-Components list. Click to select items you want to install;
clear the check box of the items you do not want to install.
9.. When you are finished specifying options, in the Start Copying Files
dialog box, click Next.
10.. In the Setup Complete dialog box, click Yes, I want to restart my
computer now, and then click Finish to complete the edition upgrade.
>> We currently are running one instance of SQL Server 2000 Standard with a
few databases. We need to upgrade to Enterprise version to use data cubes.
Should we be able to install right over the top of our current instance of
SQL Server or will we have to create a new instance?
>> Thanks in advance for any help.