Thanks for the advice on this. The 250 watt came, it went in and works just fine, and it can be recommended. Very quiet. The first one, evo by brand, had a high pitched whine. This one is just about audible and not annoying at all.
However, the lesson I learned is that when putting together an sff machine, its better to go one bigger than min-itx form factor, and matx is the way to go. Reason being, the bigger case is quieter in itself, and it will take standard atx power supplies - at least the Sliverstone one does. And this means more choice, and fanless is available too. Yes the bigger Sugo is less portable. But its still compact enough for a desktop, its a medium shoebox rather than a very small one, and its quieter even with similar levels of fan throttling. The other thing about the mini is that it has one large front fan. That's fine. But it collects dust like crazy in the filter. So it has to be vacuumed out every so often. The psu blowup was a blessing in disguise, I'd never have known.
They are both running Debian, and its getting to be time to move to wheezy one of these days. Backup first!
Al