Fastest way to alter table structure

I'm writing a database table designer (works like the Enterprise Manager one, but with restricted datatypes and some checks), and I have a bit of a question:

To alter the structure of a table, I'm currently using the same method as Enterprise Manager (create a temporary table with the new schema, copy the data across, drop the original table, rename the temporary table).

When altering the structure of a table with a large number of rows, but not changing the order of columns or adding columns in the middle of the table:
Would it be faster to execute multiple ALTER TABLE statements? If so, at what point would it become slower? (Say, changing lots of column data types, etc).Thanks

Probably always faster using ALTER TABLE.

I really doubt that ALTER TABLE statements would be noticably slower.

|||Thanks.

I was worried that if there were a lot of column data type changes there could be a lot of conversions, and a lot of overhead from going through the entire table multiple times.
|||I guess that could happen -depends upon the quantity and type of changes.