IMHO, it is quantifiable. The key to quantify interactive performance is measuring the latency or standard deviation of FPS in games. Smoothness = lower std dev, because FPS doesn't vary much. But i don't know if there is a benchmark out there that measures these.
My LOBO rig:
AMD X2 Windsor F3 3GHz 1.20Vcore
2x1GB Crucial Rendition DDR2-750 4-3-3-4 @ 2.1V
Abit NF2M mATX
Voodoo 3 2000 PCI graphics card
Gigabyte Odin PRO 550W PSU
40GB Seagate Baracuda SATA II
15" monitor
Bookmarks