Taiwan Armed Forces; The threat of China attacking Taiwan is backed up by the Chinese armed forces. The situation is not terribly favorable for the Chinese. To take Taiwan they would have to make an amphibious landing across a hundred miles of hostile ocean. The critical thing for success here is air superiority, and the Chinese are woefully outgunned in the air by Taiwan. The Chinese fleet is much larger, but without air superiority this would just provide more targets for Taiwanese aircraft. Left out of this equation is the US Navy, which could put several carrier task forces and a dozen or more nuclear submarines in the way of a Chinese invasion force. 
China is building a large missile force, especially short range ballistic missiles that could reach Taiwan in large numbers (dozens now, hundreds in the next few years.) These would likely use conventional warheads, as a nuclear attack on Taiwan would destroy what China wishes to conquer and make China a pariah in the world community.

Fighters

115 F-104s
270 F-5Es
130 Indigenous (IDF) on order
150 F-16s on order
60 Mirage-2000s on order

China has 48 Su-27s, a modern fighter of Russian design. China is building many modern Russian aircraft under license (and with technical assistance) from Russia. The rest of the Chinese air force comprises some 3,500 aircraft of 1950s vintage. Many are new, but are using 30 and 40 year old technology.


Navy
4 subs
18 destroyers
18 frigates
52 missile attack craft

China has some 50 subs, of which five are nuclear powered. They have 18 destroyers, about three dozen frigates and over 800 patrol boats. About 200 of these are armed with missiles and some 150 with torpedoes. They have amphibious shipping sufficient to lift about two divisions. There is one brigade of marines.

Army

12 divisions (2 mech)
6 armored brigades
16 artillery battalions

The Chinese army is huge, with about 70 infantry divisions (two are mechanized), ten armored divisions (323 tanks each.) Training is low and leadership is questionable. 

While the U.S. government is officially reluctant to sell modern weapons to Taiwan, the U.S. Congress is less hesitant, and proposes to authorize the sale of the following systems. 

Missile defense systems (including the Patriot SAM, which can shoot down missiles).
Aegis destroyers (which have a radar system that can track missiles and enhance the use of SAMs and friendly warplanes.)
AMRAAM AA missiles (the premier long range air-to-air missile)
Early warning radar (prevents China from making a surprise attack).
Diesel subs.
Anti Submarine Warfare equipment (the U.S. gear is the most effective in the world).