There are three ways for Windows to access an audio card:
Via an MME (MultiMedia Extensions) driver
This system has been around since Windows 3.0, and it is this type of driver that is normally installed in the Control Panel and via Plug’n’Play. Most regular sound playback (like when Windows goes “bing” on startup) happens via MME.
Via a DirectX driver
DirectX is a later system developed by Microsoft to provide developers with more efficient routines to access audio.
Note: Only use DirectX if you are sure that there is a “certified” DirectX driver installed for your sound card. If in doubt, contact your audio card vendor to check whether there’s a DirectX driver for your card or not.
More information about DirectX can be found on Microsoft’s DirectX web pages.
Via an ASIO driver
This is your best option if it is available. More and more audio cards designed for serious music and audio use come with ASIO drivers.
As stated above, ASIO does not guarantee low latency, but it allows for it if the audio card designers take advantage of its possibilities.
More information about ASIO can be found on Steinberg Media Technologies’ web pages.