Built in, quick and dirty: start powershell, execute:
gc -encoding byte -TotalCount 100 "your_file_path" |% {write-host ("{0:x}" -f $_) -noNewline ""}; write-host TotalCount is count of bytes you want to read from file.
Google 'powershell hexdump' to get much more polished/workable versions.
If you have Windows Resource Kit Tools (not exactly built in, but close) you may also use a cmd line utility called list.exe. It's a small editor with hex mode. Designed specifically to work with big files:
List Text File Tool (List) is a command-line tool that displays and searches one or more text files. Unlike other text display tools, List does not read the whole file into memory when you open it. It allows a user to edit a text file in a hexadecimal format.
List is useful for displaying text or log files remotely, and for use on servers where administrators are concerned with degradation of system performance.
