I have the PCM-5862, which is an earlier version of this (mine only has 10BT lan and won't accept K6-2, but otherwise the same). It is a decent board, but I am disappointed by the performance. The standard board only comes with 1MB of video RAM, which is upgradable to 2MB (still not much). The 5862 will not handle DVD playback due to lack of UDMA support in the SiS 5571 chipset. For some of the issues regarding this board and chipset, take a look at this thread.
One other thing to note is that the auction you linked to is for the 5862-EL, which does not include onboard audio, so you will need to use the PCI or PC-104 slot to add audio (PC-104 sound cards are hard to find and tend to be expensive).
Overall, if you're only going to listening to MP3s and you don't care about DVD/DivX or needing to use the PCI slot for a sound card, then this is a good, small and easy to power SBC for a good price. Personally, I've removed my 5862 from the car due to it's performance. It's now doing a great job as my Linux router, however! Best of luck, post back if you have more questions.