I downloaded the latest version of GIMP on my Windows 7 64-bit machine. When I try to install it, a box pops up which says "Error - This program requires Windows Service pack 3 or later. As far as my computer is concerned, I am completely updated in terms of updates. I have also looked for a Service Pack 3 for Windows 7 and cannot find one.

Hope that someone can explain what I am doing wrong.

The SP3 requirement was for M$ WindowsXP

Check your computer using Control Panel -> System & Security -> See the name of this computer

Which should get you an information panel as the attached screenshot.

My advice,

Make sure you get the Gimp installation file from www.gimp.org

Do not try and install using any of the Windows 'legacy' options, just run the installer, just use the default settings for locations etc.

A short video on installation, uses Win10 but Win7 is exactly the same. https://www.youtube.com/watch?v=klV_1PslFG4

Of course you might have already done all that, in which case give details of your exact installation and computer. Maybe someone can help.

Thanks for the feedback. On a whim I tried to open the download this morning again and, voila, it worked. I guess it decided that this isn't an XP edition of Windows after all.