Turn on your Server/Computer and boot from the installation disc...
Now, you need to wait...
Press ENTER to continue
Press F8 to agree to the Windows Licensing Agreement
Press ENTER to install Server 2003 on to the unpartitioned space
Choose to do a QUICK format else you'll be there forever!
Now, you need to wait...
Amend the Regional and Language options/settings as appropriate ensuring you click/select all the options on all the tabs.
Enter a Name and a Company Name and then click on Next to continue
Enter your Serial Number and then click on Next to continue
Choose the Licensing Mode you want to use with your server and then click on Next
Enter a Computer Name and a Password for the Administrator account
Choose the appropriate Time Zone and click on Next
More waiting...
That's it! You can now log on using the Administrator account and the password you set in the steps above.