"His ratio of goals to games is extremely high and he is the sort of character I would want to bring to the club," manager Glenn Roeder told the club's official website.
"He is fiery and strong mentally, a tough boy and he lives for scoring goals.
"He is one of those lads that keeps a mental note of exactly where and how he scores.
"In that sense there are echoes of Tony Cottee, who I believe kept a book of all his goals.
"I don't know if David does but I am sure he can tell you how he has scored his goals, and probably at what time.
"A lot of clubs wanted him and it has been extremely hard work to get him to West Ham," he added.
"Other managers recognised his potential to score lots of goals, so it was good to beat off their challenges.
"Once he knew we were interested he really had the flavour to join us, and he showed a lot of patience to make it happen."