Have used ebuyer and not had any problems (touch wood).
Have used PC World and have had problems (never using 'em again).
Horses for courses!
However, the best company for delivering promptly
and on time has to be
www.pcnextday.co.uk - bought an old socket 370 mobo from them that I couldn't find elsewhere, ordered it at about 4:30pm, and it arrived at 8:00am the following morning! Was very impressed with that.