When to replace?

There are some things you clearly know when to replace, because they wear off or are rendered useless by time. Somethings can’t be recognised as useless anymore because they have a fixed lifetime or any expiry date.

So when to replace these things? What is the best duration after which they should be replaced? The answers are available on this MSN Money article and as per the article the best duration to replace a

Tooth Brush - 3 months

Mattress - 7 years. I never knew that mettressed need to be replaced too!
Pillow - 2 years

Computer - 4 years. I would like to cut one year from this, because every 3 years the technology would have advanced to an extent where the latest software version no longer work on your computer and the parts already in your computer are obsolete and are no longer available which is a very sad feeling. And the fact that the same amount you invested on the computer 3 years ago will buy you a much more powerful machine now, which makes you weep silently. You may try upgrading the computer if you are a little tech savvy but for those of you who never opened the box dont try that at home, you better go buy a new one. Those with a laptop don’t have much smaller chance for upgrades. Glad that i don’t have a laptop