lol! it does not work that way!! if u buy a lappy with IGP! it cannot be upgraded!!
Mostly DELL uses nvidia chips(if any) soldered directly onto the motherboard of the laptop! so it cannot be upgraded!!
whereas there are certain laptops which use MXM(Mobile pci-eXpress Module) interface developed by nvidia only in those laptops can the GPU be swaped in and out nd upgraded!! (Generally MXM modules use GPU of same sizes nd specs(power consumption, TDP etc.) therefore upgrading is not a prob!)
to name a few! Sager Notebook laptops use MXM-IV slots for GPUs so that they can be upgraded easily!
Some DELL laptops use proprietary "DELL" slots for GPUs, the GPU modules for which are made & can be acquired by nd from DELL only!!
Certain Toshiba laptops can also be upgraded but use proprietary GPUs if made available by toshiba!
If u plannin on buying XPS M1530! the GPU in it is Soldered to the mobo!! so no upgradin later on!:no: