Don't take anybodies word for it either on the belt. Unless they can produce a receipt, and you look at the belt, there is no freakin way I would take there word for it. Problem is, if the belt snaps, then the engine is toast. Your talking new head, valves, piston, bent conn. rods, the works.
The engine is designed so the that if it comes out of time the pistons will slam into the valves. Only enough clearance when the valves are closed. If things start hitting, then bye bye. No if and or buts, it will destroy the engine.
VW came out with an 80,000 mile belt in I think 2003, and you can use it as a replacement, but I think the tensioner is different also. The tensioner gets replaced with every belt change so getting the right one is no biggie if bought at the same time. The belt rollers should be checked (bearings), but usually don't need to be replaced at every belt change, usually every other unless problem is found.
Also some engine mount bolts that get removed during the belt change process need to be REPLACED. If not, they will break and your engin WILL fall out! Yes, I said fall out!
Do I have ya scared? Not trying to, sounds spookier than it is. Check out this site:
www.tdiclub.com It will give you an education on the tdi motor. Check out the FAQ section at the top of the page. The info will save you ton of money, and will help you educate yourself before you purchase (give you things to look for).
The TDI is a little tricky, but if you know of all the stuff to check, or be aware of, then it's not a problem.
Hope this helps a little, Kevin