I followed this guide trying to copy session information from my old Windows install to the new one:
https://winscp.net/eng/docs/faq_transfer_config
The old session information does appear in the registry in the new computer, but when I close and reopen WinSCP, the sessions aren't there. Is there a step I'm missing?
Found the answer - newer versions of WinSCP create a winscp.ini file in the C:\Program Files(x86)\WinSCP
directory. Removing this makes WinSCP use the registry keys.