There is also a non-Pro version of the 840 that is cheaper (and slower).
My only Win7 machine is my notebook. It has 262 GB on its 500 GB spinner and there is no way I would be able to cram my data, etc. onto a 120 GB SSD. The cost of an SSD big enough for the notebook is out of the question as is putting a drive in temporarily. Besides, it’s still under warranty so I don’t want to be messing with it.
My desktop is an XP machine. It’s not compatible with Win7. According to Micro$not’s compatibility program, it would run Win7 but only with restrictions; no Aero features at all, for example. I couldn’t care less about Glass. I could live without peek but there is no way I would do without Snap (I do have an aftermarket program that emulates Aerosnap in XP but I doubt it would run on Win7. Also, you can’t use TRIM in XP and I don't want to manually clean it up (I still remember the garbage collection headaches on my C64c). And, as much trouble as I have had with the desktop, I would just as soon not mess with it. I need to keep it running anyway while I get the new machine running.
As I said, if I just wait until I’m ready to build the machine, prices will be lower and there may be something better out for the same price by then.