It already is obsolete, but that doesn't mean that it won't be able to last you several years. What it comes down to is what you'll be using it for. If its just basic word processing, music, Internet, etc. then you'll be fine.
Practically, that has the same impact. It's like saying that cars don't become slower over the years, it's the streets that become steeper ;-) The user doesn't care WHY he has to wait longer until his work is finished ;-)