There isn't a snowball's chance in hell you're gonna keep what you buy now for 6 years no way.
My home PC turned 5 this february; my dad's laptop is almost 5.5. They are both IBM and run fine. Sure, they are not as good as what's out there today. But they still run perfectly fine. And neither one has had a major problem or the OS reinstalled. (PC is NetVista x41, the laptop is some high end thinkpad)
-=|Mgkwho