ok, then you need:
1- a store
2- version control utility
3- a tool too develop togaf specific stuff (views, viewpoints, stackholder definitions, ABBs, SBBs, architecture diagrams, container documents that refers to these diagrams such as architecture definition and architecture contract docs )
4- a tool to understand various document formats to track the changes internally (including word documents and excel sheets)
let me start from bottom up,
4-I don't know any tool that is able to understand complex format like docx, even microsoft tfs deals with word files as a binary file, thus it can't track the changes done inside a document, I think you will need to compromise this point and rely more on a well structured process of providing sufficient and precise comments by whoever commits to the repository + well utilizing components in point 3
3- Archi (free) - Sparx / visual paradigm (commercial) (I have a very small experience with it but it seems to be sufficient)
2- any source control tool (git / svn / tfs / mercural) .. and if you use Archi, it's eclipse based and eclipse has plugins to most of source control tools
1- according to point 2, the repository will be defined, in case of git for example it will be a Git repository
but any ways, you will need to define a process and guidelines inside your organization for managing the architectures then the tools will just support.
Though not perfect, hope it helps !