>>
>>Thanks guys, I installed it this morning and everything looks ok. It is always better to ask first...
>
>why ask when MS says it will work (rbg)
>
>Arnon

According to MS VFP 5 also works fine being installed over VFP3 into the same directory (which is default option) when upgrading, but you will have troubles (for example with Setup Wizard) if you do so. That's what happened to me, and I had to reinstall it.
I am not gonna say that we shouldn't trust MS, but there is good Russian saying "Trust, but check" :)