There's a big difference between running straight vegetable oil and biodiesel.
A SVO system requires two fuel systems plus heaters for the vegetable oil side. You start up on diesel fuel or biodiesel then switch over to SVO when the engine and vegetable oil has warmed up, then switch back to diesel before shutting down to purge all of the veggie oil out of the system. All you need to do is make sure the vegetable oil is filtered and free of water before using it, but there is a lot of work required on the vehicle before you can burn SVO.
Biodiesel is usable for the most part as a direct replacement for #2 diesel fuel. It may attack some rubber hoses if run at high concentrations and does gel sooner than petrodiesel in colder weather. It also tends to attract water, so you need to be careful about how it's handled. Turning vegetable oil into biodiesel is a fairly simple process but it does require the use of an alcohol, usually methanol, and sodium hydroxide. These are mixed to make sodium methoxide, which is a tad on the nasty side. But, it's a no-brainer; pump it into any diesel vehicle at lower percentages like the 20% BD-80% petrodiesel blend sold at many pumps and go, with no modifications to the vehicle at all.
Alcohol as a motor fuel is a very bad choice, IMO. It's a net loss as far as energy is concerned. 'Car and Driver' had an excellent article on the subject in their July 2006 issue - you can view it on their website: