Have a look at Windows Reinstallation Guide/A Clean install of Windows XP/Vista/7/8.1: [URL]  The Dell Windows XP Reinstallation CD and Dell Windows Vista Reinstallation DVD which accompany your Windows Vista Business COA will automatically input a generic Dell product key and activate if the correct version of Dell BIOS is provided (your Inspiron 530s will have this). Essentially you purchased your PC with Windows Vista Business with downgrade rights to Windows XP. However you should review: And consider upgrading to Windows 7 64 Bit or Windows 8.1 64 Bit. If you decide to install Windows 7 64 Bit you may use my unofficial driver set as Dell do not provide up to date drivers for this model: [URL] Also if you are going through the hassle of an OS install you might want to install some newer components to make your PC faster. A Solid State Drive will significantly improve the performance of your PC. Have a look on Crucial: [URL]  
I have a Dell 530S I bought from Dell in 2009. It was loaded with Vista as the primary operating system with XP Pro also loaded as a usable alternate. I elected to use XP and have ever since. CDs for both Vista and XP came with the computer. But I can find only the Vista Product Key. The machine is getting a little slow and I would like to reinstall XP but can't do it with out the Product Key. Service tag is <ADMIN NOTE: Service tag removed per privacy policy>, Purchase I.D. 2000376115067. How can I reinstall XP? After several unsuccessful tries to get an answer here and there I even sent Michael Dell a letter asking for help. Haven't heard from him. Guess he's busy. Jim K
Need to know how to re install XP