Like most things, I guess it really depends.

My present laptop at home, which gets used daily, is now nearly six years old. When I bought it, it was close to top end and cost about US$1,000. I've upgraded the hard drives and RAM since then. It runs completely fine now for what I need it for, but is slowly starting to show its age a bit. I reckon within the next 1-2 years I will probably need to replace it.

My previous laptop before then lasted around 6 years as well. This wasn't top end when I bought it, but more of a mid range laptop and at the time cost GBP500. It didn't die on my and my parents continued to use if for a few more years.

Both laptops have been Asus windows machines. I like Asus because for both I got two years international warranty as standard.