3 computers, 2 running 8.1 Pro RTM and 0ne (Main) Win8 with Volume license. This "Main" one I wanted to upgrade to 8.1 but there's no mention in Metro of upgrade option. So I downloaded ISO of Win8.1 and upgraded from it. All was well till last stage and than black screen with only the cursor on it. Oh well,I thought, video driver does not work and I should have taken it off before upgrading. So, I installed clean Win8.1 from that ISO But the driver for Video card (ATI HD3850 Top with "amd_catalyst_12.6_legacy_win8" driver) still did not work and there was no way to register like that with volume license key.from Win8. Made a backup for win partition so I had to put it back.So, I guess I'm staying on Win8 for the time being, don't see enough of changes in 8.1 to warrant going thru the hoops or paying 200 bucks just because of them. On the other 2 computers I'm usin 8.1 just the same way as Win8 while the RTM license lasts, will see what's going to happen after that.