My girlfriend wants to build me a PC, should I let her?

Hello, I was planning to buy this for $730, an upgrade from my i3 GTX 550m laptop.

My girlfriend is telling me not to, and wants to build me one. She told me she built hers (some big one with a I7) but I don't believe her. Should I take a risk with trying to build one or buy the PC I linked. I have no experience with computers, I just play Battlefront and Fifa.

Thanks.