Yes, the clustered index will ensure that the rows are physically ordered based on the columns you specify in the index.  Some things to bear in mind:  You can only have one clustered index per table (since it is determining the row order, it would not make sense that you can have more than one).  Essentially your clustered index has to define the primary key of the table.  You might want to take a look at the "Using Clustered Indexes" topic in Books Online.  Search for "clustered indexes, overview" in the BOL index.  Make sure you use only the minimum number of columns you need in the clustered index to ensure correct ordering and define your key.