I have found it necessary many times to keep an eye on last win32 error, while using Win32 APIs in code! (Calling GetLastError() after each API usage is not feasible solution!).. In Visual Studio they have provided a very good small feature. You can write @err,hr in the watch window,
Similarly, you can use another pseudo register @eax for keeping an eye on the function return value! (If you are looking at some Win32 API's return value, you can also do @eax,hr to find out the text message behind the integer..)
Sometimes these small debugging tips increase significant debugging speed..