I agree...
I begin the upgrade shopping when i cant play a game i want to. GLquake, UT'99, first GhostRecon, anticipation of HL2/Doom3, and now FEAR all did it to me. That translates into a voodoo (cant remember, before i was into hardware...), TNT2(32meg), GeForce3ti, 9700pro, x1900xt. before the TNT2 i kinda lagged in gaming after quake. spent most of my time on C&C/red alert and really never taxed the system, lots of 2-d stuff.
That is skipping more than a generation on each step, and in the case of the 9700pro it still plays most games smooth so is still viable. I am hoping to get similar life from the 1900...