For every machine you fix by doing that I can show you 2 or more that break by doing that.
Not only that, if you use hardware that were not manufactured in the same era (i.e. ISA Multi-serial port card in an Athlon system)... they HAVE to be screwed with.
Or a Pentium 200MHz with an GeForce4600... things just do not work.
Now, I also have friend that had an ASUS A7V266 that just wouldn't work with ANY settings for long. But, a BIOS upgrade and a jumper setting fixed most things.
But, then... I am just a by-stander.