I just learned that Microsoft PowerToys doesn’t work for Windows Vista. It’s an XP-only product it seems. However, there is another easy way to do resizing in Vista;
Simply select all images that you wish to resize, right-click and select send to – mail recipient, you’re then instantly prompted to choose what size you wish to resize them to. Once your mail pops upp it’s prefilled with all the pictures as attachments. Then simply copy (select all) them into a desired folder – Great.