Hi cnr479 and welcome.

This is a US model but you can download the manual from here: -

http://www.docs.sony.com/release/MZR700.pdf

Have a look at Pages 21 - 30.

It looks to me that you can record from either a digital or an analogue input.

For analogue recording, you will need a 3.5mm stereo jack cable connected from your headphone socket on the PC to the LINE IN (Optical) socket on the R700.  You will not need any special software apart from a media player as the R700 will convert the signal to digital and record it.  Cable is like this: -

http://www.maplin.co.uk/3.5mm-stereo-plug-to-plug-lead-11422

For recording from a digital source you must use an Optical Cable.  Does your Dell have an 'Optical Out' port?