The Voyager 2 probe could be the first man-made object to travel outside the solar system in a few years, which may or may not result in it being discovered by sentient life and then sent back to "join with its Creator". V'ger 2 actually lost out to V'ger 1 in terms of crossing the "termination shock" boundary, a place where solar wind falters due to pressure "from gas in the interstellar medium lying outside the solar system". It's all very astrophysics, but suffice it to say that the probe is now about three times as far away from the Sun as Pluto, and will manage to give us a firsthand look at what's outside the solar system. [NewScientist]
You are correct, sir.
Helios 2 does, in fact, hold the record for fastest man-made vehicle, flying at ~150,000mph.
This is, however, an orbital speed, relying on the suns gravitational pull to speed it around.
Voyager 1, however, holds the record for fastest Interstellar speed. That is, going in a straight line, (or as straight as the fabric of space will allow), and not in an elliptical orbit around a massive body with enough of a gravitational pull to effect the orbits of comets ~4,650,000,000,000 miles away.
I know, I know.....I'm nit picking.
@Altanader: The Voyager spacecraft use RTG, (radioisotope thermoelectric generator), power sources that rely on the decay of radioactive material to produce energy. There are sufficient stores of this material to keep the transmitters going until ~2020.
The transmitter on the Voyagers are 23 watts. They use an antenna that is a dish, 14 feet in diameter, pointing at a receiving antenna that is 100 feet in diameter.
These antennas are uni-directional, so they receive only the Voyager signals.
They also are transmitting in the 8ghz range, meaning there is not a lot of outer interference.
This allows the antenna on Earth to receive the faint signals from Voyager. When NASA sends signals back to Voyager, they transmit using tens of thousands of watts to ensure that Voyager receives the signal.