Not sure about these, but looking through my W7 ISO image file repository *which I use for rebuilding W7 computers*,I found that the x17 ISO files seem to be 64bit versions of W7 or multi-versions. Multi-versions mean you can install any version of W7, but only 64bit OS version. Such as W7 Starter/Basic/Home Premium/Pro/Ultimate can be selected; but all must be 64bit. There is also a multi-version for 32bit OS version, but I never had need of it, since I have several 32bit flavors of W7 (mostly Starter/Home Premium/Pro) on dedicated 32bit W7 discs.
Both versions you have are slightly newer than my ISO image files. For example, my newest x15 file is x15-65804.iso dated 9/27/2014.
My newest x17 file is x17-24280.iso dated 8/2/2014. My images are now almost 3 years old, yours appear to be newer, just slightly. You should check the date stamp on those files and see if they are newer than mine. If they are, you could use them. It appears that your x15 file is for a 32bit OS install, not a 64bit OS install; so not sure how you got that file onto your W7 64bit machine (could be a mistake??).
The other thing about posting ISO files, besides the number that's helpful is the size of the file. The largest ISO files are the Pro & Utlimate versions of W7 (3.2GB - 5.49GB); same file sizes for the 64bit stand-alone, and for the 64bit Multi-version ISO files. Smaller file sizes are for x86 or 32bit flavors of W7, and or 32bit versions on stripped down W7 such as Starter and Basic versions; those have the smallest file sizes. In my W7 ISO image repository; my smallest file sizes are 2.44GB (32bit versions). So, it would be helpful to know the EXACT file size of each of the 2 ISO files you posted. Chances are if either of those ISO files (x15 or x17) are smaller than 3GB they are NOT 64bit W7 Pro images; but rather 32bit W7 Pro images. If both of those files are 3GB or larger, then you are more likely looking at 64bit OS image files; either W7/W7 Pro/W7 Ultimate or W7 Multi-version 64bit.
If someone has different information or a more concise definition--such as an MCSE who has access to MS developer or Reseller Knowledgebase (MSDN), please clarify for us. I'm guessing based on my several years of experience downloading, installing, and storing W7 ISO image files. **Thanks!**
So, post back your x15 and x17 file sizes; and we'll see what you have.
In the meantime, to answer your questions; there aren't any newer W7 Pro 64bit ISO image files that I am aware of. However, you should check the new Microsoft Catalog page, as all updates and ISO image files are now store there. You can search the WF forum using the search box for MICROSOFT CATALOG PAGE. When you see any posts from kemical, one of our Admins, there will be a link to the Catalog Page you can follow. Searching Microsoft.com site didn't turn that page up for me.