this is probably a really silly question... I just got a new lens (70-200 f2.8 VR2 yeah!) and it comes with a 1-year warranty card plus another form that extends the warranty to 5 years if you turn it in within 10 days of purchase. In the old days, we just kept the warranty cards in the boxes and never turned them in. I don't remember why we did this... was there a reason? I think the idea was we filled in the warranty card if it ever broke. 2 years ago I bought a 12-24 f4 used and it came with a warranty card that was not filled out. Do people save the cards thinking they increase resale value? I really never expect to sell this lens. My old lenses have been absolutely reliable. I am using every single one of them and they have never been in for service, including my 105 micro which got hit by a sleeper wave while it was upside down on the tripod. Got the photograph and it is one of my favorites to this day. Flash had to get fixed, but lens was ok. So, I'm assuming this new lens will give many years of dependable service... and I should turn in the warranty card right away.