Antec Three Hundred Illusion Black Steel ATX Mid Tower Computer Case - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E168... ($59.95)
Antec earthwatts EA500 500W Continuous Power ATX12V v2.0 SLI Certified CrossFire Ready 80 PLUS Certified Active PFC "Compatible with Core i7/Core i5" Power Supply - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E168... ($69.99 + Free Shipping)
Intel Core i5-750 Lynnfield 2.66GHz 8MB L3 Cache LGA 1156 95W Quad-Core Processor - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E168... ($199.99 + Free Shipping)
GIGABYTE GA-P55-UD3R LGA 1156 Intel P55 ATX Intel Motherboard - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E168... ($139.99 + Free Shipping)
G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL7D-4GBRH - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E168... ($94.99 + Free Shipping)
SAMSUNG Spinpoint F3 HD502HJ 500GB 7200 RPM 16MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive - OEM
http://www.newegg.com/Product/Product.aspx?Item=N82E168... ($54.99)
SAPPHIRE 100245HDMI Radeon HD 4850 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E168... ($89.99 w/ $10 MIR + Free Shipping)
SAMSUNG Black 22X DVD+R 8X DVD+RW 16X DVD-ROM 48X CD-ROM 2MB Cache SATA DVD Burner - OEM
http://www.newegg.com/Product/Product.aspx?Item=N82E168... ($30.99)
Total: $740.88
If he doesn't game at all, then you could go with something minimal like a 9600 or HD4650, which would get you under the $700 mark.
Edit: Do you need an OS? If you or your friend is a student, you can get Windows 7 for $30, otherwise your going to need this;
Microsoft Windows 7 Home Premium 64-bit 1-Pack for System Builders - OEM
http://www.newegg.com/Product/Product.aspx?Item=N82E168... ($99.99 + Free Shipping)
This however puts you over, if you drop down the GPU to something like this;
XFX HD-465X-YAF2 Radeon HD 4650 512MB 128-bit DDR2 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E168... ($49.99)
Then your sitting at about $800, there is not much room to slim down the build unless you go with a cheaper case and mATX motherboard.
Your next option would be an AMD Phenom II X4 build, or if you want to save a little more, an Athlon II X4, though for his needs the i5 build is the most beneficial.