When I Image my PC (new Image whenever I make a change in my system inclusing updates, added or removed apps, etc) I Image both the C Drive (OS and all apps) and the D Drive (data). I also backup all data to 2 other PCs over our network between Images.
I believe I have already mentioned that I do use Acronis, both 2010 and 2011 versions.
I have found that when I need to restore, even though the compressed Image file contains both partitions, Acronis makes me restore each partition separately. This is Ok because the D Drive in the compressed Image file is probably out of date anyway. I have only had to restore the D Drive once, and afterward I restored data from my other backups. My C Drive on the other hand has been restored numerous times. I tend to like to "play" with my OS, a lot. Because of this, I tend to vreate lots of Images because the more Up To Date my Image is, the quicker the restoration.