My main rig is coming up to 7 years old. HDD has been replaced and an SSD added, plus the gfx card went pop, but the base machine has been chugging on. I've been looking at a replacement, but it still handles everything I play @1920x1200 - though generally not at Ultra settings any more.
Antec P180 case
Q6600 G0
Tuniq Tower 120 cooler
4GB Crucial Ballistix Memory
ABit IP35 Pro
I think the only thing I use that might be older is my Saitek Eclipse Keyboard. The W key has taken a battering, but it keeps on trucking.