I think this is more of a mysql question, but....
although it seems like it'd be easier to put everything into one table, i think it's actually better to divide things up into seperate tables. have a main table where you store a user, giving them a unique id, maybe with a auto_increment column. then use that id to link all the other tables back to that user. you could have one table for logins and passwords, another for color preferences, movie preferences, etc...in each table, you only store the unique id to reference back to the user.
some of the benifits...
if a lot of people are accessing your pages, instead of querying the same table to every query on your site, the queries will be divided up based on what table the information is in. this will make things faster...
let's say you have table with id,name,address about a user.
address=555 Someplace Way
now, you want to store all of my movie preferences. if you were using one table, you could have a column movies, where you put all my preferences into a string, stored the string, and cut it all apart when you took it out of the database. this is rather cumbersome and goes against the rules of a relational database...a better idea would be to have a seperate table for movies where you store my id and movie...
then when you want to get my movies you just use "select * from movies where id=100" or something similar..
I hope this isn't too confusing and this helps you make your decision. as always, I could be totally wrong and maybe someone else has a better idea. in that case, use my $0.02 to buy something nice...