It all depends on what you are going to watch most---think about the following when making your decision:
Do you watch movies mostly on your screen or do presentations?
4:3 Ratio is still the standard for presentations where data and power point, excel type files are used mostly
16:9 is used for most movies, DVD, Bluray, and most TV providers offer hidef channels which are 16:9 ratio as well
Most television shows are still broadcast in 4:3 but 16:9 is taking over more ground everyday.