Not long enough, obviously.
Oh, sure. They'll play along for a little while, they let you install Linux, play a few games of tetris, then bam! Your video card dies. Or has it? It might be a trick to get you to open the case. And when you do, what horrors do you find? I was once attacked by an ethernet card. Another time I discovered a swarm of black widows that had taken up residence on my pentium motherboard. (Clearly, they had been drawn in by the totally evil vibes sent forth by the processor)
There is only one way to escape the horror. Buy a laptop. Not only are the critical parts usually pretty easy to replace, but if something really big dies, your only hope is to throw it out and buy a new one. Clearly, economics at it's finest.