With apologies if I sound pessimistic, I expect I'll have to start using 10 more as Microsoft punishes those who don't. But I can still take my time. ;) Getting ready at my own pace, I moved my XP Mode VM over to VirtualBox. I gave it a try in 10's Hyper-V [Microsoft's VM software], but found that for simply running a few VMs in Windows, Hyper-V is sort of one of those Run -- don't just walk away things.
Now, if you can manage it you're probably better off starting with a fresh XP SP3 install in a new VM. If that won't work for you, you can download the VirtualXP.VHD from microsoft[.]com. Three or four years ago I migrated a working copy of XP Pro to a V/Box VM, & everything worked, if a little slowly -- I tried last year & the same [but updated] copy of XP Pro would barely run, to the point of being unusable. I don't know what changed, & I only had the one copy to try, so it's entirely up to you if you want to take that to mean it won't work today, or give it a shot in case something was messed up with my copy of XP or the conversion.
In my case, once I found last year that I couldn't migrate a more current copy of XP Pro, I set about installing the software & drivers I needed in the XP Mode VM that I had been running since 7 was new. That took a while -- long enough that I didn't want to do it again, so I migrated my existing copy of the XP Mode VM. There's a big caveat to doing that -- the XP Mode VM as set up in 7, uses Windows XP Mode base.vhd together with Windows XP Mode.vhd, rather than a single virtual hard disk. That meant doing a full image backup running XP Mode, so I'd capture the data on both disks, as if instead of 2 there was only one. I restored that backup to a new, dynamically expanding VHD, but V/Box wouldn't have it -- I wound up using a giveaway of Paragon Go Virtual, which did work, but gave me a V/Box format virtual hard disk -- a .vdi.
One error I made, was setting up the new VM to use SATA for the hard drive -- as set up for 7's Virtual PC, the XP Mode VM apparently uses IDE, so I went with that, & it works well. The AVG Free security software was a mess -- I had to download & use their full removal tool, then reinstall -- but otherwise there's really nothing to write about... it was basically a matter of creating a new VM, selecting Windows XP for the version, selecting the .vdi I got from the Paragon app, starting the VM, running the setup program for the V/Box additions to tailor V/Box for XP. For a key I used the old one I had for XP Pro. I did create a new, empty VHD, & then basically cloned the .vdi to it -- substituting that .vhd file for the .vdi in the VM's settings you can't tell the difference, and XP Pro was still activated.
Now, Hyper-V... it's probably a great tool for what it's intended for nowadays, & that's running servers etc. -- for a simple VM in Windows, not so much. That's not to say it was hard to get running -- once I got 10's Hyper-V installed & set up, following Microsoft's online docs, I really just had to point it to the V/Box .vhd file & it ran. Then I started reading the help files to see how to share files between the VM & 10 [the Host]... not finding anything I could use in the included *Windows 8* help docs, I took to Google. Again finding mainly Windows 8 info, seems there's basically no easy way to do it. You can set up remote access in both 10 & the VM, & hopefully get something working that way. Or you can set up another network adapter for the VM, and share files & folders the same way you share them on your network. Bleh...
With 7's XP Mode, remote access is already configured so I see & access anything I want on the Host PC. With V/Box I simply select which files/folders I want to temporarily share on the Host, & I change which folders I want to share a Lot, so I need quick & easy. Hyper-V has advantages for servers no doubt, &/or with Azure etc., and it *might* be more capable of using hardware GPUs, but for what I use VMs for, all I can see is more work. On top of that, it doesn't appear that there is a Hyper-V equivalent to V/Box's Additions for XP.