Yes, you can use the REW setup on your Windows PC system for measurements. I will need the files created when done with both speaker measurements via email. You can once the dspNexus XMOS device driver is loaded use it as the test system with REW and your UMIK-1 as well.
The Audio Weaver license is part of the purchase of the dspNexus system. After purchase, the email address you want to use is setup for you to login to DSP Concepts to activate your system license. Danville Signal will email you a Dropbox link to the version of Audio Weaver needed to run your dspNexus.
Audio Weaver runs on Windows PC's with a USB connection, the speed depends on the CPU.