Connecting to a computer VIA Digital Pins

I was wondering if it would be possible to use the Digital Pins on an Arduino (Duemillanove) to interface with a computer. I'm using the Arduino's RX pin for a RFID Reader serial input, so I guess that means I would have to use a software serial library.

What kind of hardware/connections could I use for achieving this?

um hm, the first thing that popped in my head was connecting it to the printer port

but software serial + anthother usb (or any other serial to pc converter) chip might do too

I would move the RFID to softserial and use the ordinary RX/TX for the computer interface.

Softserial on "ordinary" digital pins do not go through the FTDI chip and can not talk to the PC without extra hardware.

Actually pretty simple to obtain a second serial link to your PC. Either using software serial library or the additional hardware serial ports available in the Mega board, you just require an additional USB serial converter module. It will handle the 5 volt logic level from the Arduino pins and move the data to and from via a additional USB port on your PC.

Here is one example:

There are also USB to TTL serial cable assemblies available very cheap, but you have to make sure they come with driver software that works with your PC and have a connector type that you can somehow interface to wire to your Arduino I/O pins.