AVR in system programming (ISP)
You'll have to power the board. The +5V connection shown on the connector comes from your board and is used as a pull-up for the reset signal: the 10k\$\Omega\$ resistor keeps reset high until it is pulled to a low level by the transistor.  

The latest PCs are often no longer supplied with an EIA-232 interface. In that case this programmer may be an alternative.