Haha, yes, glad modems are a thing of the past. Mostly.
They always gave me plenty of headaches.
To the point: Most modems do not echo anything by default; you have to enable it.
Type the following in minicom (followed by enter):
If that doesn't work, experiment with what <enter> sends: CR, CRLF or LF
If that doesnt work try again using 9600,8,n,1
Get a standard RS232 cable, dont try to solder one yourself, you will only shoot yourself in the foot.
Get a null-modem converter plug while you are at it, just in case.
Buy a Sweex USB-to-serial converter.
If all this doesn't work, get the drivers from http://www.ftdichip.com/Drivers/VCP.htm
and get the 32 or 64 bit version.