Sigil for older Windows machines

I know Sigil works fine for Windows 7 32 bit, because that's what I am using. But what about Vista and XP? I find people still using one of those (including my wife, who won't replace her Vista desktop because she doesn't want to have to deal with the thousands of files she has stored on it).

I did search MobileRead, but it seems that one can't restrict a search to the Sigil forum, so most of what comes up is irrelevant.

Thanks!