I've had all sorts of problems integrating hulu desktop so that it functions as intended. I started by installing hulu Desktop Integration found HERE
This would provide access to hulu through MC, but there were issues when I tried to close hulu. More than 50% of the time, when hulu closed and tried to launch MC, the windows taskbar would stay in the foreground. I just couldn't resolve this issue no matter what settings I messed with: in MC, windows or hulu.
I ended up downloading this mcpriorty program to see if it would fix the issue, and it did.
First off, Hulu Desktop fully supports Hulu Plus and HD. However to be frank Plus is not really worth it since most all the content is available free anyway when using a PC (browser or Hulu Desktop). Very little content actually requires Plus but if it's what you want then sign up. Luckily you can cancel at any time to give it a try for a month and go back to free if it's not worth it.
I just added an icon for hulu desktop into WMC. Selecting the icon launches Hulu and minimizes WMC. After you exit hulu desktop, just hit the start/green button on your remote. It brings you straight back to WMC. I've been doing it this way with Zero problems for well over a year.