We are looking at some real nice vector source pages here in the fifth part of the series. They offer a tremendous amount of vectors for you to choose from to use in your projects. I have added nonetheless a couple of links to two great collections. Well the one on smashingmag, if you don't know it, is quite awesome.
Vectors Source Sites
http://vectorart.org/
http://qvectors.net/
http://coolvectors.com/
http://www.123vectors.com/
Vector Collections
http://naldzgraphics.net/freebies/a-collection-of-free-adobe-illustrator-floral-vector-files/
The real ultimate of collections in this category has actually already been assembled by Steven Snell at Smashingmag, check it out:
http://www.smashingmagazine.com/2009/01/16/the-ultimate-collection-of-free-vector-packs/