Perhaps this would be better in a Xampp forum but I thought I'd try here first.
When I go to the install.php I get this (and more besides)
wp-config.php file. I need this before we can get started. Need more help? We got it. You can create a wp-config.php file through a web interface, but this doesn't work for all server setups. The safest way is to manually create the file."); require_once('../wp-config.php')
I have completely different database names and directory structures to my previous version of WP (I had to uninstall it all before updating XAMPP) - I have the feeling that somehow something is going on in the background still but I can't think what it could logically be ...