Check reviews for both retailers. Also double-check the return policies, and if you can, use a credit card to purchase your system. You won't be able to take advantage of GenTechPC's "cash discount" but you'll give yourself maximum consumer protections should you have problems with the system and you need to return it and the retailer quotes you some outrageous return charge or something (e.g. AmazingFactory's purchase debacle). Using a credit card gives you the option to reverse a charge if the retailer doesn't work with you on the return etc.