I ask because my beloved Dell Inspiron 8200 is on it's last legs (trackpad not working correctly & struggles with high-res graphics). I bought it in 2002 & so it's 7 years old this year - which I think is pretty good going as it's been used fairly heavily every day. 
I'd really like to switch to
& buy a 17" Macbook Pro - if I did, do you think it's reasonable for me to expect to get 7 years heavy use out of that too? To other Macbook owners, how many years have you got out of it before you had to upgrade?
Many thanks,

I'd really like to switch to

Many thanks,