You can remove these features easily within the Messenger options.

1. Click your display name and click More Options - or press Alt on your keyboard to bring up the menu bar and click Tools > Options
2. Click the Contacts tab on the left
3. Untick the Show favorites, Show groups and Show the tab bar checkboxes
4. Click OK

Enjoy a less cluttered contact list!

1. Click your display name and click More Options - or press Alt on your keyboard to bring up the menu bar and click Tools > Options
2. Click the Messages tab on the left
3. Untick the Show expanded footer in conversation windows checkbox
4. Click OK

WARNING: For ADVANCED users only!

Fisrtly we need to find the Vendor and Device IDs for your graphics card, so we need to access your Graphics Card properties:

1. Right-click the desktop and click Screen Resolution
2. Click Advanced Settings
3. Under the Adapter tab click Properties - this should bring up the properties for your graphics card
4. Click the Details tab
5. In the dropdown, click Hardware Ids
6. See the picture below and write down your VendorId and DeviceId in a notepad file so we can use it later. Mine were 10de and 0e22 respectively.
   
   
   
   
7. Click OK and close everything we just opened

Now we need to enter these values into the hardware blocklist:

1. Open the registry by typing regedit into the Start menu or the Run dialog
2. Navigate to the following key: HKEY_CURRENT_USER\Software\Microsoft\Windows Live\UX\HwBlockList\0\0
3. Look through the numbered folders and create a new key numbered 300 (it can be any number not taken, but we don't want it to be overwritten when new exceptions are added -thanks Chris).
4. Within the new key you created, right-click the empty space and create 4 DWORDS: DeviceId, Flags, Options, VendorId
5. Remember the ids we wrote down earlier? Enter the values into their corresponding fields and set Flags and Options to 1. Here is what mine looks like:

Close the registry and restart Messenger, the fancy shmancy animations should now be disabled.

Credit: withinwindows