Due to the closure of the official TheSims2.com website the below links are no longer valid.
In order to download any of the official patches, if you require them, you can do so at the ModTheSims.info patch archive

Here is a list of the official patches released by EA and the links to download them from.

Base Game
Sims 2 CD/DVD Patch

Expansion Packs
Sims 2 University

Sims 2 Nightlife

Sims 2 Open for Business

Sims 2 Pets

Sims 2 Seasons

Sims 2 Bon Voyage

Sims 2 Free Time

Sims 2 Apartment Life

Stuff Packs
Sims 2 Family Fun