I no longer use Microsoft OS, so have not got any 'feel' for what kind of performance to expect.
Kind of echoing Stuart's comments, from a different angle.... One thing does strike me about both systems... 500GB disks? That is not a lot in today's terms. IMHO this would be worth thinking through... is the system used for storing photos as well as editing? And are you likely to buy a new camera (with more pixels) at some point, which would increase storage even more? Note though I am not saying it's bad, just saying "think it through". Having thought it through you may conclude that 500GB is fine, and I would be in no position to disagree. At the end of the day you could always attach an external disk for more storage, but that would add a few watts to power requirements.
Memory is also relatively modest by today's standards, at 4GB. Not sure whether photo editing tools are particularly memory-greedy, I think they might be? Personally, I'd want to make sure it is at least upgradeable if it proves inadequate.
I've not had any HP desktops, but I have had a couple of their pretty cheap 'proliant' servers. Always seemed very well made.