Asio is a driver used with a sound card.
It reduces the latency or speed the card can send sound data.
The more expensive a sound card is the better it is at producing sound.
or the clarity of the sound with frequency ratings of sounds. Hz.
The interface the card can connect to on the computer is also a factor.
Most new cards support the Pci-e interface where as older ones run on the Pci slot or interface of a motherboard.
Pci 66Mhz Pci-e 100Mhz.
If your friend is doing mid music production, then i suggest a pci-e sound card with 24bit studio output.
Be prepared to pay from about £150 all the way up to £350 or more. The cards should support Asio/Asio 2 drivers.