Oregon
Land area: 154,491.858 square km (95,996.79 sq miles)
Total population: 3,825,657
Population density: 24.76 persons sqaure km (39.85 per square mile)

Source: 2000 US Census, http://quickfacts.census.gov/qfd/states/41000.html

Taiwan
Land area: 35,801 square km (13,822.8 sq miles)
Total population: 23,142,460
Population density: 639 per square kilometer (1,674.22 per square mile)

Sources:
Geography of Taiwan, http://en.wikipedia.org/wiki/Geography_of_Taiwan
National Statistics, Republic of China http://eng.stat.gov.tw/point.asp?index=4