No, your movies, music, pics, documents (basically things that are not a program) can stay too. You will just need to navigate to them when you want to use them or add their current location to the windows libraries.
What I mean by that is (for example) pictures normally reside in c:\user\
username\pictures. (this will only have the sample pictures in them since its a fresh windows install) But your old 1TB HDD has the existing stuff in the same location but under another drive letter. What I suggest is create a new top level folder for each item (Pictures, Videos, Music, Documents) on the 1tb drive (lets call it D: for now) Then copy the pictures under d:\user\
username\pictures to d:\Pictures (repeat for the other types) Then, when done, you can add D:\Pictures to the Pictures library locations and the will show up.
To add a new location to a library, bring up explorer and int he left hand pane Right Click on the library you wish to update (pictures in our example) and then left click on properties. In the new windows you will see a list of the current locations and there's an 'Include a Folder' button just below it. Click on it and navigate to the folder you want to include in that library (D:\Pictures for our example)
After a month, when you are sure there isn't more you want to rescue from the d:\windows folders (like browser favorites, emails, ...) you can delete it should you choose to