6670 in Dell Inspiron 660?

I wanted to upgrade my friend's Dell Inspiron 660 with my old XFX 6670 1GB DDR3 card. I believe his PSU is only 300 watts and was wondering if i should use the card. 

Ya it should be fine I did that to my first computer and it was fine I used a 5570 in a hp computer but the same thing really