(I know nothing about webhosting.) I wouldn't be a reseller. Just looking at the Profi plan for more space for a personal site. My own computer's OS is Windows XP Home.

Does this mean that I can't use CPanel? (It sounds like an executable that runs locally on Linux systems only.) It sounds like I would have little use for WHM, anyway, but I like what CPanel can do.

No you can use both WHM and Cpanel since they are executed on the server running linux. You access WHM or Cpanle through Internet Explorer.

Since your Windows XP has internet explorer you are able to access both control panels.