PE Explorer
PE explorer is a very powerful tool, it is a very good dissembler but it has a lot more functions. I’m not going to go into it because there is to much to much to cover, but I would definitely have a look at the help file that comes with PE and see what cool stuff you can do. PE explorer automatically unpacks programs that have been packed with ‘UPX’ protection. I thought I would just mention this incase when you load an ‘exe’ in PE Explorer that is packed with UPX PE Explorer automatically unpacks it, this is why the file size of the executable will change (increases). Click here to see a picture of PE in action and here to download PE Explorer. While you are on there site check out there other cool tools! :-)