It depends on your PC. USB has evolved over the past 15 years, without changing connectors at the "host" end to reflect the changes.
iPad (and some other tablets) want to draw at least 1 amp from a USB power supply. The USB standard prior to USB 3x let this port be current limited to something lower (1.1 was lower than 2.0).
Some PCs have USB ports that will power tablets, optical drives and other high current devices, others will shut down the power if the device draws too much. Some high load devices will charge more slowly on a low power USB port, iPad may not charge at all.
My deskside PC has 8 USB ports of 1.1 and 2.x vintage. At least one of these will provide power for devices drawing up to 1 amp, it is marked as such. Some of the others might, I haven't tried the iPad on all of them. You can try with the ports you have on your PC, they will protect themselves from overload on the power line.
IPad, fron iPad2 at least, the data connection cord is the charging cord, whether original iPod 30-pin or the newer Lightning cord. iPads needing 1amp ship with a different charger from iPhones and iPods happy with less than 50 milliamps. Cords are the same. I make it a point, buying USB charging devices, to make sure they are rated at least 1 amp on each port. These will usually be a little bigger, a little heavier, than chargers with lesser ratings.