1) I suspect that the machine may be too old to support Windows 10, there may not be drivers for it. What is the make and model of the machine or, if homebuilt, what components are in it?
2) If it can run Windows 10, you are probably better off doing a clean installation. If you have old software that's compatible with XP, some of it may need to be udpated, or may simply not work with 10. XP to 10 is a pretty big jump.