The biggest tool i can recommend using is an SVN client and CVS server.

The difference it makes to larger projects is huge. The main advantages are:

- If a team member updates code you get notified and asked to download the latest version
- It stores all previous code copies in individual revisions
- You can highlight all the changes which have been made in any revision
- If two people work on the same file at the same time it can smart merge the two, this usually works but can be reverted and done manually if required.


You can get a free CVS account (with limited space) here:
http://cvsdude.com/

And a free SVN client here:
http://tortoisesvn.tigris.org/

The few hours you spend setting it all up is more than worth it.