First of all, the plugin issue is only with the 64-bit version of Photoshop. You don't need to use it if you don't want to. 32-bit applications work just fine with 64-bit version of Windows, so you can still use the 32-bit version of Photoshop. There is some performance improvement with the 64-bit Photoshop, but only very advanced, multi-layer Photoshop work will benefit appreciably from using the 64-bit version. Don't worry about it. Just stick with regular old Photoshop because you're not doing anything nearly that complex. Professionals might have some interest in 64-bit Photoshop, 99% of everyone else doesn't have much use for it.

And regarding the Poser "Area Render" function, you have that backwards. I don't think you understand what the Area Render function is. The Area Render function is when you select a portion of the full scene to render. Say you have an 800x600 render, but you only want to render the table that's in the scene. You select that area of the render like the rectangular selection tool in Photoshop or the crop tool, and it only renders that small box. In that case, it is using the old internal renderer. Any time you render the whole scene, it will use the external renderer which is 64-bit and multithreaded. You will see a very large performance difference if you switch to 64-bit Windows and Poser Pro.

As for DS vs Poser, there's no contest between the two. Poser's render, despite its flaws, is still more advanced than what DS has to offer. DS might be easier to use, but Poser can definitely achieve a higher degree of realism. And then of course, there's bagginsbill's VSS prop, which is designed for use in Poser and that alone is enough for me to stick with Poser. Nothing else makes skin look as real.