Indexing Questions

Sorry its been a while since I was taught about indexes,
Can I place indexes on both FK fields of a Associative table?
and what is the recommended number of rows to place an index on a table for SQL server (if different from other DBMS)?
and also whats a clustered index?Yes
I put clustered indexes on every table though not necessarily for performance reasons. Regarding nonclustered indexes, the number of rows is less significant than the number of pages those rows occupy - this depends on the "width" of the rows and fillfactor.
The last question is really fundamental - I suggest you read the entries in BoL re indexes & their associated structures otherwise you will just find yourself asking piecemeal questions and having to peice it all together at a later date. Better to get some understanding and then ask about anything you haven't quite grasped.|||I guess I would like to know why you ask that question

It's kinda like DBA 101