I'm thinking an i5 with 8 GB RAM, an SSD for booting and a 1 TB HDD, but I don't know if I can get all that for $500-ish.

We have a ten-year-old HP whose Pentium D dual-core processor can no longer do all that we're asking of it, which is the following worst-case load situation:

Recording a few tracks in Reaper while handling a Chrome-based WebRTC conversation and allowing for me to remote in via Teamviewer at the same time. The latter two processes are more intensive than I'd realized, and are currently pushing the CPU load over 100% according to Task Manager. We're currently on Windows 10 Home, which we would like to stay with, unless there's a really good reason to go with Pro.

Any suggestions for a sturdy machine (it's left on all the time, rebooted every few days, FWIW) would be most appreciated. Hoping for something "off-the-shelf," rather than taking the time to build one.