You have USB Headset, plus Onboard sound? Open Windows sounds and go to recordings look for Stereo mix for your Onboard sound (if not there you can't use this method sorry) Right click Stereo mix, Properties then click Listen now tick the box and select your Headset Apply/OK
Now go to TS and select the default playback has your Onboard sound Like Realtek and test you should now have Teamspeak sound come back through to your Headset.
With Fraps this will not record the TS, but if you use Dxtory you can still Record both TS and game but it wont be mixed together so you can choice when to keep TS or delete it
If that Method Dont work I used to do it this way before understanding what Stereo mix is. I made a Youtube video
http://www.youtube.com/watch?v=7pqyHaVY6TY Now I dont recommend using this method no more because it was very fussy when it wanted to work.
Hope this helps.