Question : tranfering from cassette audio device to computer file

hi there! I have some audio classes that I've recorded on a device that records telephone conversations - and i want to convert to mp3 or whatever so that I can have them on my computer instead of on the cassette tapes. (the machine has a headphone jack - but when you attach a headphone - it only plays in one ear)
I found a youtube video that explains how to do this using moviemaker -- but you have to have an audio in jack - which the laptop computer i own doesn't have!
I'm wondering if there is some type of plug (what would be be called?) that will allow me to connect from the jack of the cassette machine, to either the usb or the vga or whatever and let me somehow do this without buying another machine.
thanks!!

Answer : tranfering from cassette audio device to computer file

I actually have one of those A/V adaptors with the audio and video plugs. It's great, but unfortunately won't just take audio: if it doesn't see video as well it doesn't work.
So, let's take the easy solution first. Griffin has its iMic, which will do the job -- digitally as suggested previously:  http://www.griffintechnology.com/products/imic

Here's the diff between the analogue and the digital solution: All audio starts off as analogue so there has to be a conversion to digital done somewhere. With using the mic input of your Laptop the Analogue to Digital (A/D) conversion is done inside the Laptop.  In using the iMic the A/D conversion is actually done inside the iMic and the signal enters as digital through the USB.

So just to step through the line transformer solution.
The first link that you posed would be the connector that goes LAST and the minijack enters your Laptop mic input.
http://www.audiogear.com/cgi-bin/shopper.cgi?key=AdptFxMsm&preadd=action

So what you need is a cable to get out of your telephone machine and into the line transformer -- the MALE XLR from the line transformer then connects to the FEMALE XLR from the cable that goes LAST.
It may be simpler to go with the iMic.