Same here. My desktop is blazing fast still and its a 2009. I bought the highest end dell I could find in early 09 running windows vista and it runs 8.1 pro with zero problems. Even by todays standards its still a fast computer with 6gb of ram, 1tb hd, and a 2.5ghz i5 processor. My laptop is a 2010 with similar stats and I plan on keeping those two up and running along with my surface pro 2 until hopefully 2020 with Windows 10.
My first real solid computer was a dell bought in 2001 with XP and I kept it until 2009 so I think the lifetime of the device can easily be stretched beyond 2-4 years depending on your preferences and what you need/want to use.