Notebook sound problem - notebook sound card needed?

Hey everyone.

I really hope you can help us out here, moving into this field with little to no knowledge of laptop sound. here's a bit of back story:

I have recently moved my gf's laptop into the front room and hooked it up to the tv with the intention of watching high definition movie files. The files in question are hitting the 8gb mark and I was unsure about whether the laptop could handle it. Fortunately it seems to hold up pretty well until a film hits a loud or sound-intense section which is when it begins to stutter. I figure this is due to the on-board notebook sound. Would you guys agree with me?

So jointly my questions are:

Will some sort of sound hardware fix the problem we've got?
If so then what is best? PCMIA card or USB card?
And finally, which out of the following is best for price/performance compromise if I were to get one:

Creative Sound Blaster X-Fi Xtreme Audio Notebook 7.1 Sound Card - http://www.pixmania.co.uk/uk/uk/56 [...] ?srcid=867

Creative Sound Blaster Surround 5.1 USB Sound Card -
http://www.pixmania.co.uk/uk/uk/46 [...] und-5.html

or is there a different one all toghther you would recommend.

Thanks a hell of a lot in advance - Cheers