Sun sets us on fire. Pretty nasty way to go. [ Though oh so satisfying when he did it to the Annoying One. ] Garlic is annoying and crosses burn, just like holy water. Not enough to kill, unless you get really creative.
If you want to kill a vampire... go for a beheading or a good old-fashioned staking. Right here. [ He brushes his fingers over the spot where his unbeating heart is. ]