I don't know about the Nv15 demo. If a cat sh*ts on the floor, I always make someone else clean it up. Same deal here.
As far as Quake3, it's a tie. 50% of the time I clean it up. The time demo is just a standard 'movie' that runz using the quake3 demo, and comez back with a max and min fps. So, it's like a benchmark that is standard, no matter what computer you are using. Pentium4's always 0wN on this one.
UtBench is the same deal. It's another cut-scene using the UT engine. It won't give you a max/min though, so you have to watch it really closely or have it log to file and search through the damn thing afterward. It's much more processor intensive, so you see the FPU work a lot harder to hammer it out.
Dunno about Undying. If there is a console command 'show fps' or something, then yeah; you can bench with it.
the nv15 demo was a special q3a demo made by nvidia, the difference between it and the other demos is the fact that it has a really high polygon count, download it, its really cool (if u have a good system)
demo001 comes with quake (as does 002), and anyone with q3a can play those
The first LAN party I went to was at a PETA convention. They booted me when I shot a crab in HL!