[woodsyi]

My wife has been asking me if I can record her playing so that she can hear her own playing.  She has acoustic/electric guitars that she can use with SWR California Blonde Amp.  http://www.instrumentpro.com/P-SWRBLONDE.html  It has balanced line out.  Can I use this with a Microphone preamp into PC to record? If not, I only have ECM800 microphone.  Can I use this for recording?  What software is recommended?

[HChi]

Unless you have a mixing console, a few good mics, and a recorder already, the easiest mean may be getting a portable recorder such as  Zoom H4, http://www.sweetwater.com/store/detail/H4/, or the like.  It will also give you the flexibility of connecting the direct line out from the guitar amp to the recorder for electric guitar playback.

The other major advantage of having a portable recorder is that she can operate the recorder without your help!   

[AdamM]

Good advice HChi

You can also try one of these:
http://www.m-audio.com/products/en_us/FastTrackUSB-main.html   $99
USB to your computer, so it's easy to use. One line level in, and one mic level in, so a vocal mic and the direct out from your amp.

It has some software with it, or you can use 'Audacity' which is a great two track recorder that's free.

If you want to use two microphones, and have a few more options theres:
http://www.m-audio.com/products/en_us/FastTrackPro-main.html  $199
It's also USB, has 2 mic ins, 2 line level ins, a good monitor / headphone layout.

Good luck!
/A

[HChi]

As Adam recommended, if you like (more) computer interfacing capability and also something of decent quality, you could also take a look of T.C. Electronic Konnekt series.  They are a tad bit more expensive than Adam's recommendations though.  Good luck!