My suggestions (assuming he only needs the box, and already has a monitor, keyboard, and mouse):
MoBo: ASUS P5B Deluxe Socket T (LGA 775) Intel P965
CPU: Intel Core 2 Duo E6300 Conroe 1.86GHz
RAM: G.SKILL 2GB (2 x 1GB) DDR2 667 (PC2 5400)
Video: SAPPHIRE 100189L Radeon X1900GT 256MB GDDR3
Sound: Creative Sound Blaster X-Fi XtremeMusic 7.1 Channels
HDD: 2X Seagate Barracuda 250GB 7200 RPM SATA 3.0Gb/s
DVD Burner: LITE-ON 16X DVDÂ±R DVD Burner W/ LightScribe
DVD Reader: LITE-ON Black ATAPI/E-IDE DVD-ROM
CPU Cooler: ARCTIC COOLING Freezer 7 Pro CPU Cooler
Case: Cooler Master Centurion 5 CAC-T05-UW Black
PSU: OCZ GameXStream OCZ600GXSSLI ATX12V 600W
Now, there is some headroom, and I assume he wants a better soundcard for his music activities. Also, if he needs a monitor, you might think about dropping one hard drive , in which case he has about $250 for a monitor. That's enough for a very nice 19" and close to the cheapest 20" LCD screens.
Do note I selected DDR2 667 RAM. You stated you are not overclocking this rig a whole lot, if at all. Thus, there is no need for DDR2 800, and DDR2 667 saves some good money. Now, I do advice to take a serious look at the E6400
. It's only $40 more, and worth that extra money.