Hardware advice

Go for the 840 Pro and don't worry about declining write speeds. Also the "current" AMD lineup is pretty slow and power hungry compared to Intel.

Apologies if this has already been suggested...but one particularly good upgrade/addition, especially how much their price has fallen in recent times--would be a smaller capacity SSD to use as a boot drive in conjunction with your mass storage hard drive.

The amount of speed gained from having an SSD to boot your OS and most frequently used programs really is incredible if you typically use HDD's. Not to mention the increased reliability/cooling you get with a SSD that has no moving parts.

I replaced my main HD with an SSD some time back and am quite pleased with the increased performance. The only drawback was a message that I received from Defraggler to the effect that I was attempting to defrag an SSD and that they do not last long - do I want to proceed? :/ I now only selectively defrag when fragmentation exceeds 10%.

Please DON'T defrag your SSD... defragging is a method of making read/write operations more efficient on physical disks that have to spin to certain points to have data read/written - SSDs do not have to spin at all and thus don't see any benefit to defragging.

Defragging is BAD for SSDs and can shorten their life
Defragging is (theoretically still) GOOD for Hard Disks and can increase performance

Back in the Windows 3.11 days, I was in charge of the installation, configuration and maintenance of about 20 PCs that chemical process operators used to communicate with distributed process controllers (which I also designed, configured and maintained). When the hard drives of these machines became defragmented, not only did performance suffer, but they totally crapped out (the programs would no longer run). I had to use Norton Speed Disk to get them running again.

I understand what you are saying Hobbes, and today PCs crapping out due defragmentation is probably no longer possible - I just have to adjust my antique mindset.