During more than year of practical experience with client computers I had a few cases when the only radical solution to help clients and their computers was re-installations of their operating systems. It was happening in cases when the computer was really slow and the whole usage of a machine was really painful and problematic experience. After adding an extra RAM memory and re-installation the OS computers significantly speeded up and everybody was happy.
Unfortunately, in 3 out of 20 cases this operation was only partially successful and not because computers stopped working completely but because after a few months of relatively good performance problems came back or something else happened which disabled the computer completely from any performance. At the beginning I was really disappointed with these cases and wanted to repeat the same operation for a while but after a few weeks of thinking about it I realised that an each computer has its lifetime and it is really not worth revitalise something what can stop working in next day from an unknown reason.
From a gathered experience I know that it is worth to talk to a client about the options for future computer usage as most of computers today are relatively not expensive and the cost of repairing a problematic machine can be much higher than a value of a new computer which after a relatively short tuning process will work for about 2-3 years without any bigger issues. This decision must be made what is much worth - repairing a ageing computer which has not warranty or investing in a new computer which is more up to day and a warranty from manufacturer.
What would you do?