I can not find an x55d, only an x55vd which is a 4 year old model of laptop.
For graphic design you want a laptop with an intel i7 ___HQ processor.
There is a big difference between the ones ending in a U and the one ending in HQ. The U model is the battery efficent and the best cpu is just a 2 core 4 thread with turbo into the low 2 ghz range. HQ is a 4 core 8 thread (for the i7 model) with turbo at 2.8-3.2ghz (depending on model).
I cant really give you a recommendation on a specific model with no knowledge of what country you are in or what vendors I have to look at.