I don’t have that problem in Server 2008 64bit with WinRAR 3.71. Are you sure you have selected Shell integration at the WinRAR setup? (Can be accessed by opening WinRAR -> Options menu -> Settings -> Tab Integration -> Icons in context menus check)
Context menu’s are different per user. Maybe you installed all applications under the Administrator account, and are now logged in into a limited user account you created. If for example in Editpad Prod the context menu settings can’t be set in the program options, log in onto your limited account, right click the installation file of Editpad Prod and choose “Run as Administrator”. After installing the application under the limited account the icons should also appear in that account!
Good luck! 🙂