win 8 vs win 7?

[Asp]

Currently I'm on WinXP.

I run some old software: DOS GEM, a bunch of command line, and some older Windows programs from c 2000.

I want to keep running all these, but also want to use some current software that has dropped support for XP.

Have got a 512GB SSD and ready to try to move to a new(er) OS.  Probably will set up VMs to run old software that won't run native.

Was planning on Win 7, but I see that's also now losing support.

Is Win 8.1 any better supported, or any advantage to that over 7? Disadvantages?

How much space should I allocate for an install of Win 8 on a desktop PC?

[Tripredacus]

40 GB for Win7/8 OS install is fine but only if you are going to be managing space/data by using other drives. On physical I never use smaller than 80 GB disks but for a few VMs I've used 40 GB without an issue for the server-based equivalents. I can't really answer the 7 or 8 question. I use DOS programs multiple times a week on my Win7 but I use DOSBox for it.