I got an MSI motherboard with the 785G and ATI Radeon 4200 chip. What's the best graphics card for about $150 that I can use that can run Crossfire on this thing? Or would it be better to just stick in a better/different card and ignore the crossfire?
By CrossFire i think you mean CrossFiring another card with HD 4200 right? if so then do it because Hybrid CrossFire is mostly for power savings and won't have a great impact on performance,so get a single fast card and there is no need to CrossFire it with the
integrated HD 4200 card.
If you want to CrossFire buy 2 high-end cards and CrossFire them,but with your budget go for a single fast card like HD 5770
Check out this chart from ATI. Granted the 785G chipset is not on the list, but notice that the 780G is and what cards it works with. It will only hybrid crossfire with the 3450 and 3470 cards. I am assuming the HD4200 only works with the lower 4350 type cards.