There is no enumerated power in the Constitution that specifies the Federal Government has the authority to fund the arts.
The Four pillars of Conservatism:
1) Limited Government
2) Obedience to the Rule of Law
3) Rights of the Individual
4) Personal Responsibility
This proposed spending by Bush violates 3 of the 4 (#'s 1,2, and 4).
One could argue that it violates #3 as well: Individuals should have a right not to have to pay for the arts...