|I recommend you use a separate partition for your programs. As I mentioned earlier there are some you may want on the C partition but most should be elsewhere.|
That say you don't need to backup as much data when you do backup. Your programs partition isn't going to change much, if at all.
Using a partition for downloads is a waste of a partition. Windows 7 creates a download partition by default on the C partition. If you need/want to keep downloads then move them to a different partition at that time.
Your photos and mp3 files are alrady compressed files so there is no advantage to imaging them and no advantage to keeping them on separate partitions. What may happen is one partition will fill up and the other will have lots of room.
You can keep all files that are compressed on the same larger partition. Just use separate folders for each type of file.
Games on a separate partition is OK.
Did you use all the space on the drive? If you ever decide to play with a different operating system it would be nice to have a separate partition for it. Preferably a primary type.
As long as there is room you can create a third primary partition.
Basically, you want to separate things to different partitions based on how often you will need to image/backup those files.
The OS is dynamic, changing weekly or sooner. Your MP3, photos, movies, etc. are different. The files themselves don't change. You just add more from time to time. Allowing Window to save thing in your documents folder and periodically copying the new files to the folder on a different partition works well. Then, of course you should make a new backup or just add the new files to an existing backup.
I will try to stress the advantage of separating programs and the OS. Programs are linked to the OS. They won't work anymore if you have to re-install the OS. However, if you have the OS and the programs on different partitions and you need to restore the OS from an previously made image, all your programs will continue to work. That would be the case if they were both on the same partition too. The difference is the size of the data on the partition will be at least twice or three times are big. This makes performing regular backup/images more time consuming and you may not do them.
The OS is by far the most important thing to keep current images of. All the settings, and updates are really time consuming to redo.
Your MP3, photos, movies, etc. will all be accessible not matter if you need to re-install or restore. They are not linked to the OS. They may be linked to a player or viewing program is all.