It comes down to if drivers are available for the hardware. Retro gamers are the experts with this.
Enter these keywords in youtube's search:
XP gaming PC
Austin Evans "The Ultimate Windows XP PC Build" video has some good info.
I'm going to be investigating this more soon with a new XP32 build.
I'm planning on using large RAMDisks (61 to 125GB) to speed things up even more:
XP32 will run on a SSD, but the VMWare virtual machines will run on RAMDisks. SSDs are fast, but slow compared to RAMDisk. It'll take a while to fully boot or shutdown, as my script saves/copies the VM folders to/from SSD (not a big deal as I reboot maybe once a month when GDI and User object leaks force me to). When using RAMDisks for OS & data, a UPS + sinewave backup generator is mandatory. And a stable system is a must. I have no patience for any crashes and over the years I have tossed lots of hardware and software if it causes any instability.
XP will get a larger pagefile.sys on a dedicated RAMDisk, probably around 30-60GB. I currently run a single 5GB pagefile.sys on a 5GB RAMDisk, which limits me to a 5GB max commit charge (before XP will auto-create another pagefile on a slower drive). My current typical commit is 2 to 4GB, so not an issue today, but in the future it will be, as I give the virtual machines more locked RAM. I'm not sure how XP's virtual memory system is going to behave with 3GB for the OS and a 30-60GB pagefile.sys. Uncharted territory here and should be interesting.
The challenge will be finding a motherboard that supports 64 to 128GB RAM and has XP drivers available. Boards with lots of RAM slots are usually Xeon server motherboards and I don't think XP works with any modern Xeon CPUs. I may have to look at AMDs offerings. I'd like to use ECC RAM, but I believe that's Xeon only.
I've not decided on which RAMDisk yet. It has to be one that gets created before the pagefile.sys and uses unmanaged memory (RAM XP32 can't use). Superspeed RAMDisk does this (with some obscure registry code, documented by the gamers on oczforums). It's extremely stable and fast (not a single BSOD and I've been using it 24/7 since 2011).
There are a few other RAMDIsks that claim to offer similar features, and I may test them out.