High speed internet speeds are up to 7Mbs depending on how far you are from the central office. Runs accross your phone line.
Fios has speeds up to 50Mbs (this depends on the area you live and the amount you want to spend). Does not use your phone line
Speed being the obvious benifit to the Fios. But depending on what you use the internet for. Sometimes you just waste money for the faster speed. HSI is cheeper obviously. And if all you do is a little shopping, email and general surfing, HSI speeds are probably adequate (assuming you can get between 3-7Mbs). If you do a lot of P2P sharing, video downloads, music downloads, or online video gaming, then you would probably benifit from the faster fios speeds.
if you could get FIOS get fios its around the same price as the DSL 7.1mbps deal and you get closer to what your paying for. even if you qualify for 7.1mbps dsl you may not reach up to 7.1mbps but with fios your alot closer to what your paying for. if your considering cable please do some reasearch first on the providers in your area .
P.S my advice if you have the option for road runner/time warner cable dont. yea no contract but.... what a pain.