At the top of the message there should be a notice about outlook blocking images, and you can right click this to put the senders address into your allowed to show images list.
As for allowing what attachments can be seen, I found some plugin for Outlook 2003 that allows you to move extension between type 1 (no access at all) and type 2 - you can get to it if you want. It's called "Attachment options" and I got it from
http://www.slovaktech.com/attachmentoptions.htm
HTH