ADDITIONAL COMMENTS: My 2nd Gen Asus G1 Lappy is getting old, figured it's time for a new rig. Building something to play Borderlands and Modern Warfare 2. Want to be able to swap out a few parts in a year or two to keep it somewhat up to date to prevent buying an entirely new rig. Been a while since I've built a desktop, hopefully not missing anything obvious. All help appreciated, thanks.
I don't think Hybrid CrossfireX will work between a 5850 and a 4200. Different, genearation, one is DX10.1 and the other is DX11, not to mention one is massively more powerful than the other. Even if you did get it working, it would perform worse than just using the 5850 due to scaling issues.
Since you are interested in upgrading, I would recommend getting a 790FX chipset based motherboard, for better crossfire support. The Asus Crosshair III Formula is popular. I like the MSI GD70, it four PCIe 2.0 slots, but that's more than you need. Getting any 790FX board will be the best option if you want to add a second 5850 in the future.
Also, with your budget you could probably get a quad core like the Phenom II 955. The 720 will work well for now though, you will just have to upgrade sooner.
Hey 1ce, thanks for taking the time to give your input =)
I wasn't 100% sure about the hybrid crossfire, couldn't really find any information on it but it most likely that i just looked in the wrong places. I was actually looking at the Crosshair III Formula and the 955 as options. Chose the M4A785TD-V EVO just because of the potential for hybrid crossfire and the lower price point. Am definitely going to get the Asus Crosshair III now since it does open the window for future upgrades more.
I will have to redo the pricing and see how well a Phenom II 955 fits in. Even if it is in my budget, I'd prefer to stick around the $1500 mark and not really test the upper part of my budget. Perhaps some more research is needed.