Great thread!
I have purchased the DSATX DC-DC power supply and upgrade my sound card from an old PCI Sound Blaster Live! to SB X-Fi XtremeMusic.
I am extremely happy with these two upgrades, a nice and juicy power supply with shut down controller gives you the worry free car pc experience that requires no extra switch to worry about, just use your ignition and your car pc “embedded” into your dash became one of OEM equipments. (not really, but people don't know your car may think so!)
The sound card upgrade gives more details to the music, sounds much better!
I will try to post some recent works on my carpc and post some pictures.