ok wait let's get one thing straight, VC is an incredible player and one of the best in the NBA. He is a franchise player for a reason, he is VERY talented.
Now as far as the Knicks' need for him goes, he woudl be a drastic upgrade as a plyer (barring all injuries). IF he were to play at SF, which i think he is VERY capable of palying because he can pull down 5 rebounds a game and cut through the lane, he would dramatically vchange the knicks' offensive capabilities. He can slash through the lane as well as our very own coveted Marbury can, but he is larger and stronger thus can also dunk.
Now as far as the need for a player like VC (in his current form, uninjured) goes, it is immense. Even if he were to dunk for 15 points a game from teh SF position and pull down 5 rebounds a game, he would bring an incredible amount of momentum towards the knicks. The reason we were lacking shooters in this postseason was because of the loss of Allan Houston. He is back, and like another post has indicated, he will not have to change his gameplay much because of his injury. He may not be able to play 40 minute games, but his stroke will still be the same through the 20-30 mihnutes he plays. This leads to a trio of Allan Houston, Stephon Marbury and Vince Carter in the backcourt who are all capable enough to be franchise palyers and require a 1.5/double team on them. This will lead to MANY open looks. Vicne Carter will also compliment Marbury's quick style very well.
Now wouldn't this be a nice starting rotation(parenthesis are predicted pts/rebs by me):
SG: Allan Houston (17/2)
PG: Stephon Marbury (22/1)
SF: Vince Carter (24/4)
PF: Michael Sweetney (15/9)
C: Erick Dampier (10/12)
Total by starters:
Points: 88
Rebounds: 28
Now of course these are very rough predictions, by just a fan but i do think this team would be a contender.