I couldn't speak as to the cause of your problem, it's possible the card was on its way out already, maybe jostled during installation of the SSD and that was the "last straw", so to speak. The issue you're describing sounds like problems I remember having with a 7800GT a long ways back (and a 7950GT I'd gotten as a replacement) where they were overheating.
That aside, for replacements for both parts, 1 quick question. How many 6-pin PCI-express power cables are coming off of your power supply? As I recall the 8800GT required one, but the PSU might have two.
If you have only one, then a Radeon 270 would be a good bet. If the power supply provides two, you could look at a Radeon 270X or GeForce 760.
I think it's worth pointing out there there are expected to be new video cards launching this fall, starting as early as next week with the Radeon 285, which may shake up the mid-range a bit. It's possible there will be cards with more oomph that will fit into a smaller power envelope, so while you could buy one right now, you might at least want to wait until the 285 launches next week. If nothing else, it may result in some price drops in other cards.
For sound, if you want to replace the X-Fi and keep using a discrete sound card, Asus' Xonar series is well liked. They have a few different models, but basically you've got the option of the Xonar DSX for about $50, or the DX, which adds some extra stereo virtualization capabilities (great if you game with headphones) for about $80.
Also, I highly recommend checking out TR's latest system guide:http://techreport.com/review/26747/tr-j ... stem-guide