pro mini upload works on ubuntu, doesn't work on win7pro64

I have a pro mini 328 5V/16Mhz and a ft232rl ftdi with all 6 pins connected.
The upload works perfectly through usb on ubuntu from the 1.5.2 ide witout installing any additional drivers or pressing the reset button, but on win7pro64 (different machine) it doesn't.

Error: avrdude: stk500_getsync(): not in sync: resp=0x00

I tried installing the arduino drivers and the recommended ftdi drivers.
I think windows sees that I connected something (the ftdi icon appears in the device list).

PeterH's suggestion in this thread solved my problem