What do i need to convert my bike from a 7 speed to a 9 speed?

[Jack Davies]

I have an older Trek 2300 pro that i want to convert to a 9 speed STI setup instead of the old 7 speed downtube shifters. I currently have a Shimano 9 speed cassette, Shimano tiagra shifters, and a SRAM chain. What else do i need so complete the conversion?