For your auntie, it maybe better to go with a company with good customer. Some members here think EVESHAM is good, but I do not any experience.
As for Dell, the service is excellent if you are working for a large company or one of richest man in the world (no kidding), but I do not know how they deal with "small" individual customer.
Tiny.com owns by Times Computers which is a big box shifter, and you can find out how they are doing in this formum.
PCWolrd is also not a bad place to look if you know what you want and be very very FIRM with shop assistant/manager. You can easily take back if anything wrong.