GPU 1: GigaByte ATI Radeon HD 5870 ($220)
GPU 2: MSI Lightning ATI Radeon HD 5870 ($222)
Just hunt on NewEgg & Amazon for 5870s once or twice a day. They tend to pop up cheap (< $230) and sell out within a few hours.
What is the difference between all of the different 5870s? Are they all about the same?
I'll be able to tell you on Wednesday how the MSI Lightning compares to the Gigabyte. My main 2 rigs both use GigaByte 5870s. The rig I linked is about to be hooked up, waiting on the power supply to show up. I also just bought another MSI Lightning on NewEgg this morning (bought 1 and they were out of stock before I could buy a 2nd for a complete rig).
My understanding is that all the 5870s are BASICALLY the same performance. Slight variations, mostly due to temperatures you can run them out with the slight changes in how each the fans/heat sinks are set up between brands. I do know that you want 1 gig cards over 2 gig cards due to the savings in power consumption.