you DEFINITELY don't want to take greyhound...believe me. I was a Hopkins undergrad and had a girlfriend at University of VA, which I would visit every other weekend and I took greyhound once...and only once. Too many shady ppl, and the bus stations are even shadier, so believe me, if you can rent a car, do it!
If you drive, just go 95 South to 495 West silver springs, till you get to 66 West, take 66 W until you get to exit 153, 29 South....not the one that says to "Centerville", but a couple exits after that one.....29 South is a straight shot to the middle of campus at UVA...though it turns into Emmitt street around that area......good luck....
Man, I miss C'ville...such a great little town!