Well, many reasons for which i don't like OEm. First they are bloated with lot of software you will never need.Originally Posted by PChammer
Also, what hardware they use inside, you don't know and if you decide to change the operating system, its almost impossible to find the drivers sometimes as you really don't know what the hardware actually is inside. Most often , you will find no drivers for the hardware if you changed or upgraded or downgrade your operating system as the new OS isn't supported by OEM for that hardware.
The price difference too plays a crucial role as the difference for the same configuration between a custom one and OEM is too high.
In India, almost every Home computer will be a Custom one assembled with the help of local vendor or technician. :P