A source code control system allows you to go back to previous versions and do comparsions of versions. This is important because it is not uncommon to break one thing while fixing another. The version comparisons help figure out how that might have happened.

Secondly, source code control systems are an efficient storage method because they store only the changes to files rather than multiple copies of the files.

Thirdly, despite the extra pain in the neck that CVS and similar systems are to administrate, they allow multiple copies of the code to be checked out (usually by different people). When the people commit their additions and revisions, the system looks to see if there are conflicts in the areas that have been worked on. It demands that the conflicts be resolved before a new version is released.

Another benefit of all of these systems is that they enforce a certain discipline of documenting what you have worked on. Actually, I have found that documentation more useful for billing or job review than I have for benchmarking the progress of a job, which is its original intent.

You may think that only you will be working on this code, and that may be very true. But, you 12 months from now, after working on some other branch of this project or some entirely different project, you will appreciate any structure and documention that exists. It will help you get back into the depths of the code elements.