The solution should be written in c++ using Win32 API (no MFC). Can use WTL.
Should run in the background and log any text from chat applications such as Skype, MSN, etc. including both ends of the conversation.
A good example for techniques to grab the text can be found in this article:
The example is for Windows Mobile, but can be used for a desktop application.
Should record Skype calls, including Video, Voice and chats. Should record Google Talk (video, voice and chats) and also Facebook chats.