Why is a PC any different to a radio, or other electronic item? They last for a lot longer than that.
Some PC's do, that is absolutely true. But some don't. Thus my warning is based on averages. If you have bought quality equipment and not the el cheapo stuff then absolutely you should see that equipment last longer than three years. But not everyone does that and some people do not realise this and as such everyone should be aware of the risks after that 3 year period.
As other have stated, a PC is quite a bit different from a radio. I would be inclined to compare a radio to a PC sound card rather than the PC as a whole...
Quite amusingly, I had typed up a reply on my laptop, went to post it only to find I had lost my connection to the internet, so this is a retype as I went to my 8 year old PC to see what was happening. Fortunately it came back again - but I notice that right this minute it has again disappeared - so you will have to wait to read this reply!
Oh and in my 8 year old PC the fan on the video card died so I'm expecting to have no video one day and it wouldn't surprise me if one day the damn thing just doesn't turn on. SWMBO has a budget and it doesn't include a new PC as yet.
Whilst linux may be an option for some, as Colin rightly points out it is not nirvana either. While there are some very good distributions available, my favourite is OpenSuSE, if one is to work with linux then one be prepared to get udner the covers, use the command line and generally pretend to be interested. I think you can probably end up with a non-functional PC running linux a lot easier than with Windows.
That damn internet connection still hasn't come back...
Oooh - it's back = post quick!!