I've made about ten on-line purchases from Novatech over a period of four years or so. That fact alone speaks volumes as they have consistently provided a solid, reliable service with accurate item descriptions, good quality components and speedy delivery.
I haven't purchased one of their pre-built or pre-configured systems but I find their motherboard/CPU/RAM upgrade kits to be excellent value. Their graphics cards are also competively priced.
I had to RMA an item once, and it was quickly and efficiently dealt with, with a two day turn-round. I've not had to return an item for refund so I cannot comment on their attitude or speed in that respect.
Tech support is more than adequate even to the extent of one of their sales personnel calling me back when he couldn't answer a question I had about the compatibilty of a component once he had researched the query with their tech support people. And it was a 'good' answer.