Yea, it depends on the type of driving light used. If you are using some Aux. PIAA HID lights then you gonna want some high amp relays. But anything else I'd just go with a 30 or 40 amp relay from Radio Shack.

Heres some RS numbers:
900-2394 - 5 pin 40 AMP SPDT $2.99
275-226 - 4pin 30 AMP SPST $5.99

The 900 # must be special ordered.