/dev/sda equivalent in Windows
Solution 1:
Yes, \\?\Device\Harddisk1\Partition0. Win32 programs like dd.exe should understand this (see its documentation for a few more examples), although .NET-based ones might not.
The Windows equivalent of /dev, \\?\, can be browsed using WinObj.
Most graphical disk-imaging programs just present a list of disks... use one of those.