Nikon D3100 PC compatibility?

I recently purchased a Nikon D3100 and am having much trouble with the video. The playback on the camera is excellent but the playback on my PC is terrible. I have a Dell Inspiron 530 and also a Fujitsu tablet. I have a brand new class 10 SD card as well. When I tried playback on a friend's mac, it worked smoothly. Is there any solution to my issue?

The only thing that I can think of is that your computer is too weak to do HD video

you can try to upload the video to your computer before you play it back, because then it will read off of the hard drive and not the memory card. Try that before you do anything else.

after that, it all lies on your graphics card, perhaps you need to upgrade that.

I wouldn't say your entire computer is too weak but perhaps your graphics card is too slow to handle the huge data stream HD video generates.

When I first converted to HD I had to upgrade my graphics card as well be it was choppy.
I went directly to Dell and I've got a 1/2gb card that plays the video very well.

It's obvious to me that your friend's computer has a higher speed graphics card than yours. Look into an update, my card was about $80.