for standby, very easy to get around, just go into power management in control panel and set it never turn off even idle
an external sound card cost around £50, but a 512MB mp3/wma player will cost about the same, if you use wma format (good quality at low bit rate), 512MB can take about 8 CDs.
£54.99 Ebuyer 512mb MP3 Player with LCD Display, FM Radio and Digital Voice recording click here
If you have a lot of music, you can get a 20GB HDD mp3 player. S-Media GP2000 20GB MP3/WMA Player USB2 with FM Radio, Line In and SD/MMC Card Reader £117.49 click here