After reading the article that Al posted above, yes there are a small group of users who could benefit from a Windows Manager, rather than a DE. One of the things that I like about the MATE DE of Linux Mint, not much resources used. Xfce provides further resource savings.
I am doing this to reserve resources, as this is for a very low end computer.
Could you tell us a little more about your hardware, so that we may can assist you better? It's kind of hard imagining one having a computer that's in use that's older than two of my own (one unused since late 2013). These would be the IBM Thinkpad T42 with 2GB of DDR RAM & I believe a 1.73Ghz single core CPU, the other unused one is a Dell Dimension 2400, with 2GB DDR RAM, and a 3.06Ghz (Northwood) HT CPU. Both of which will still run good if called to duty, though not like the ones I have of 2006 origin or newer.
If your hardware is older than those (both 2004 models), then you really have an antique on your hands. Still, I believe that even the two computers listed above would benefit from the Windows Manager, solely based upon the description.