I had an X3100 in a Dell Laptop, it was terrible, even worse than the 8400m GS, avoid the X3100 in my opinion, get a nice 7xxx gt you'll be very happy that way.
XFX 7950gt $189.99 at newegg
I run a pair of these in sli, bang for the buck this card is as good as it gets, mine has heat pipes, that said, be sure to have good ventilation, they do get a bit warm.
Originally Posted by bgamari
I would go with an Intel integrated chipset (the X3100 has decent performance and open-source drivers). On the other hand, if you do wish to have something with better gaming performance, ATI's new cards should soon have full open-source drivers and specifications, and will more than meet your needs.