What is Considered a Large Database Table?

[eluser]Fielder[/eluser]
Thanks, a couple other questions come to mind.

Does microsoft SQL or any other database perform better with larger tables than mySQL? Should I be preparing to migrate to a different database sometime in the future once I hit the million record tables in mySQL?

How is querying performance affected (if at all) if I have a million record table, and I'm doing a simple SELECT * FROM table AS t1 WHERE id = 548435? id would be indexed and unique. Are JOIN queries more taxing on a table of that magnitude? I'm wondering what types of queries are intense on a table of that size.

When these big companies start getting huge databases, besides optimization, do they do things like break large tables up into multiple smaller tables, or split the database and duplicate it on 2 or more physical servers?

Any links on database optimization 101? Want to make sure I've got a good schema right now while it's just beginning allowing me to do those optimizations in the future.