This links right back to the same book, so it's really the same source. A whole lot of links to the same book does not equal a lot of sources proving that conservatives give more than liberals. If they counted Warren Buffet in with the liberals, that raised our average household income a bit. I wonder which camp Bill Gates is in?Should have given you this link - one of a whole lot saying jackasses give less than elephants.
Also, we don't get to count the money we hand out to someone, or the donations we make to someone in need if he or she is not a registered charity, so I don't think you can really pin these numbers down.
Having said that, it is entirely possible that conservatives give more; I certainly can't disprove it. I feel very comfortable with the amount I am donating and with the causes I am supporting, none of which engages in proselytizing those who may not be interested in being converted.