Yes you need a power supply for all 3.5 inch drives. The laptop drives on the other hand will power off USB. Is this a SATA or ESATA drive? You can buy an enclosure for the SATA for around 35.00 and 70.00 + for a good ESATA enclosure. The cheaper ones do not work to well with the ESATA. If it's EIDE then you can get one off OKorder for around 12.00. Good luck.
NO, YOU NEED A POWER SUPPLY
you could make it work if you are planning to make a usb cable for power and another one for the receiving and sending of data. but if you are meaning to just plug in the usb cable from the hard drive to a port then no you can't a usb is ussually 5V and i don't think that's enough to power up a hard drive. just buy a power cable they aren't that expensive. if you have enough money to buy the external hard drive you wouldn't mind spending 5-10 dollars for a power connector.
