Here's some savings:
1x AMD Athlon II X3 450 Rana 3.2GHz Socket AM3 95W Triple-Core Desktop Processor ADX450WFGMBOX
1x BIOSTAR A880G+ AM3 AMD 880G HDMI Micro ATX AMD Motherboard
The CPU is potentially unlockable to a quad. The motherboard has an ATI Radeon HD 4250 which will handle casual games and older titles decently (about equal to a 9600GT) so you could probably get away with dropping the video card unless he is a gamer. If he IS a gamer then take the savings and go with a beefier card.
You didn't specify whether the hard drive he has is SATA or ATA/IDE. The board I linked to will handle either. It can also unlock cores and has VGA, DVI, and HDMI ports so he could use either a monitor or TV with it.