Absolutely great! I started a thread in the SH4 forum on modifying the underwater view, as I like the dark murky water. I got good advice on changing those settings, and also on changing how deep into the water you can see.
http://www.subsim.com/radioroom/show...8&postcount=10

Where this ties in with the new card is in the fact that before turning on the transparent water was something I could only do for a minute or so just to admire it. Frame rates were impossible so to play it had to be disabled and even then it was very slow.

I keep loading up SH4 now just to look at the lovely water and the boat underneath it! :D

Bottom line: With what I'm doing currently the card is perfect. I've also read a post by one user who has pretty much the same setup, including the single-core processor, and to my surprise he says he's running SH5 with no problem. I'm quite happy right now.