I installed the SSD last night; reinitialized the HDD and installed W'10 on the SSD. The system boots noticeably faster now (but not as fast as I expected), but the most surprising difference is how much quieter it is. The HDD was making a lot of noise when the heads or arms were moving, and they were almost constantly moving (seeking, I guess). No "clicks" or other bad sounds, just a lot of activity. The OS is on the SSD now and the program and data directories are on the HDD (and the swap file is on the HDD, more on that later), and now all that commotion has stopped. The computer wasn't really idle, it was running World Community Grid workloads, but all that is still on the HDD. So I don't know what all the activity was.
I created a 30GB NTFS partition at the beginning of the HDD and put my pagefile on that. Windows wouldn't let me use all the space available but I used most of it. Now I keep getting helpful notifications from Explorer that my P: drive is almost full and I should delete unecessary files. (of course it's almost full) I dismiss the message, and after a while (maybe when I sign off/on, I don't know) it comes back again. The P: drive is hidden using that NoDrives thing in regedit, but Explorer still knows it's there. I turned off all Explorer notifications to make it stop pestering me, but I dunno if that was a good idea.
I initialized both drives to GPT instead of MBR. Windows Setup didn't like that for the SSD, but it didn't insist that I change it. Did it not like GPT just because the drive is so small? It actually recommended GPT for the large drive. Or perhaps what it didn't like was i was installing on drive 1 instead of drive 0. (are those number assigned based on which SATA socket on the motherboard the drive is connected to?)
I've been experimenting using the MKLINK /J command to try to trick software installers -- especially Chrome because it insists on using the system drive -- into using my big D: drive but not having a lot of luck. (MKLINK creates symbolic links, hard links, and something called a junction which I think is just like a hard link but for directories) I created the junction and it looked okay, but when I ran the chrome installer it failed but didn't tell me what the failure was. BTW, MKLINK is not available in the Windows Powershell, but it is still in CMD.exe. So open a Powershell in the directory you want to work in, then type CMD to start the command processor, and now you can use mklink.