Unlike previous Outlook mail clients the new one in Office 2007 uses the dpi of an image when displaying it if it is embedded (rather than attached to) an email (Menu:Insert Picture).
Older versions used to just display across the pixel width of the image. If when using web/email sized images produced by my actions you find the image being displayed too small in an email then as a temporary measure use the handles to resize the image.
If I have written actions for you in the past and you have this problem then please email me your action file and I will update it at no cost to you.
Stephen