The Windows HCL can be a useful troubleshooting tool for some STOP errors (Blue Screens of Death) and Device Manager error codes. While rare, it's possible that some errors could be caused by general incompatibilities between Windows and an installed piece of hardware.
The Windows Hardware Compatibility List might also come in handy as a reference when purchasing hardware for a computer you intend to install a newer version of Windows onto. You can usually assume that any PC hardware is compatible with an established version of Windows but it's probably wise to double-check for compatibility with a version of Windows that hasn't been on the market long.
Links to operating system specific versions of Microsoft's HCLs can be accessed at their Products Designed for Microsoft Windows page.