C:\Users\yourusername\AppData\Roaming\Adobe\Adobe Photoshop CS5\ has things under it if that’s the sort of path you’re seeing documented.
The AppData folder is hidden so you can’t normally see it to double-click on. You can fix this in two ways: 1) enable Show hidden files, folders and drives in Explorer / Tools / Options / View / Advanced Settings or 2) Once you’ve clicked into your username folder, just type the \AppData at the end of the c:\Users\yourusername already visible in the Explorer’s address area, then hit Enter, and continue double-clicking down into the folder structure.
In my win 7 systems the ACR presets are in
Thanks SSprengel and Robert....the folders were indeed hidden, so clicking on "Show All Folders" helped me find what I was looking for. Much appreciated!