"Clustering and association rule mining"

newack

Hello,
I have to do clustering and profile generation on the data( contains 8000 entries).It's a binary file.
I did clustering using tool cluster.exe and could find result that if number of clusters increased, error decreases. Now I used gen-profile.exe for profile generation and inputed the file obtained from clustering.
i changed min. weight and got differnt patterns.
Now the question is, on what factor should i decide that one pattern is better than other? how can i decide cluster number?
please help.