Windows only: Replacement file manager Double Explorer adds tabbed browsing and a dual-pane view for navigating your files, but unlike a full replacement application, it embeds a normal Windows Explorer screen into each pane.
The biggest problem with many of the alternative file managers is that some of your shell extensions aren't going to work anymore, so Double Explorer simply loads up the Windows Explorer view for each tab or pane that you are browsing in. Once you've installed Double Explorer and launched the application, you can simply start browsing and accessing your files — though you might want to turn off the navigation pane if you've got a small screen.
The application also has some nice extra features, like a favourite folders toolbar, and it remembers your latest locations when you restart. Double Explorer is free and open source, available for Windows only. Readers might note that it's still a little rough around the edges in some places, but definitely worth a look if you're in the market for a new file management application.