I thought it was worth a thread because it surprised me to some extent. I was sufficiently bored to torture my 10yr old Dell by putting Vista Ultimate (trial) on it. To my amazement it runs perfectly, as well as my 4-5month old lappy infact! It's spec isn't exactly ordinary though...
It does prove though, that if at the time you are willing to spend £10,000 (I didn't pay for it!) you can have a pc which will live that long. It's lived through Windows NT, Windows 2000 PRO, Win XP Pro and now Vista Ultimate, quite amazing really. (Never had a single hardware fault either, touch wood).
I tried to prolong the lifetime of all my PC's I've built by using the best components I could afford/buy @ the time.Although my present PC is 5yrs+ in age,it runs Vista home premium according to the MS checker yet I stuck a trial of ultimate on it.I wouldnt like to have kept ultimate on though as it was slow as hell.
I have also previously loaded XP Pro onto an ancient laptop which has 233Mhz CPU and 96Mbs RAM + 4Gb HD.Ok so bootup took about 30 years,but it worked. :)
I'm not saying your old machine would have struggled running Vista though as its still a hell of a spec.