Recently I bought new computer, with small SSD harddisc and large fixed HDD. The problem is that I want to sync the whole Dropbox here, but the SSD disc is to small for it. I solved it by hardlink of Dropbox to HDD - it means, the Dropbox folder is still in my Users account, but physically the data are in D: harddisc.

How to do it, step by step:

1. Install Dropbox on the computer, and created the Dropbox folder in standard location, i.e. in Users account on C:\ (in my case C:\Users\Zeleny\Dropbox)
2. stop the Dropbox from syncing for while
3. move the whole Dropbox folder into the new destination - in my case d:\Zeleny\Dropbox.
4. and now, create the hard link, using command prompt:
   1. open the command prompt as an administrator (click on Windows button on keyboard - the one with the window on it, and type Command Prompt. This will find the command prompt file, you right-click on it and choose Run as administrator. It will open the black window for typing the commands)
   2. use the mklink function in command prompt - for more details how to do it see this website, namely the section Symlinks via Command Prompt
   3. in my case, I typed:

       mklink /J C:\Users\Zeleny\Dropbox D:\Zeleny\Dropbox

   4. the result is that the new Dropbox folder is created in C:\Users\Zeleny, and this folder contains all the data from Dropbox folder in D: drive - physically it looks like if these files are really located in C:\Users\Zeleny\Dropbox, and the Dropbox program keep syncing them there.

Note: seems like it's possible to sync Dropbox also to network drive, but it needs special hack: https://gist.github.com/pavank/2961448