Inexpensive solution for back up PC

I am setting up a secondary computer as a studio backup computer. I need a decent soundcard that can work well with Sonar... I have a breakout box I can use if needed, his is something for emergencies. Don't want to spend a lot. Don't even need balaced in's for this. Any recommendations?
 
- Alan

There are inexpensive Behringer's if that is what you want.  
 
I have a backup for my 8 channel MOTU 896Mk3 Hybrid and its a Focusrite 2i6.  Its not 8 channels like the MOTU but I could get by if the MOTU shot craps during a recording session (that is usually 4 tracks or less).
 
I would suspect a PC failure would be more likely than the recording interface unit.  
 

Considering there are a few decent interfaces that can be had new for $150 or less, I'd start at that baseline.  Because I'm on Firewire, my two backup units are the TC Electronic Konnekt 24D and the Konnekt 6, both of which I picked up cheap on Ebay.  I actually use the Konnekt 6 as a general-use sound card for my main PC.  Great DA converter/headphone  amp, and it cost me all of $50.
 
For USB2, I'd go with the Steinberg UR12 ($100 new).
 
If you're okay with B-stock or used, then shop around on Ebay or Reverb.

The Focusrite 2i2 works well for me as a descent 2nd unit.  I can travel with it because it is USB powered and can be driven by my laptop.  Fits easily in my laptop back pack.  The 2i4 is similar with more outs, but a little more costly.