For those times where you have no choice but to use it.
The .emacs file can be placed in C:\.emacs, but a better option for (shared) Windows 7 systems is C:\Users\yourusername\AppData\Roaming.
AUCTeX is easy. Full instructions. Just download and extract to the Emacs directory.
To use unison requires a bit of extra steps. Up to date binaries are here (along with links to some other things that you might need if they aren't already installed). The main difficulty is getting transfers over ssh to work. Download unison-ssh and follow the instructions there. There is a comment a ways down that explains how to setup keys. The summary is:
Use puttygen to generate keys
Save the private key as C:\id_rsa.ppk (or whatever you want)
Edit the appropriate unison prf file (found in C:\Documents and Settings\<username>\.unison on XP) to add the line: sshargs = -i C:\id_rsa.ppk. Other required options like port numbers (-P instead of -p for some reason) should also go here.
On the remote machine, add everything in the box in puttygen that says "Public key for pasting into OpenSSH authorized_keys file" into ~/.ssh/authorized_keys.
Once all that is setup, you should be good to go.
Example preferences file
The following example is what I use to backup to the GT physics file server. It is a lot easier to just connect to the phys-file server using the file manager than to set everything up for SSH. I exclude a path here because it is huge and I don't need everything there to be backed up to the file server. It is useful to include the default profile for using common settings, such as fastcheck.
include default root = D:\mvd root = \\phys-file\mdepalatis3\lab ignore = Path simion