My 62 year old brother wanted me to build him a XP gaming rig that had games for single play only - i.e. no internet connection. So I had some spare motherboards laying around and other spare parts. I found a guy about 20 miles away selling new PC cases that were brand new but ~20 years old that he had kept in his garage. So I bought 2 new cased for only $20 a piece that also included a new power supply, then I actually built 2: one for myself and one for my brother. The hardware build was easy, but the software installation took a long time. I had to search and get some copies of older games off the net. Each build has XP Pro with 3 gig of ram installed. More than enough to play older games on XP.
These older games play great on somewhat modern hardware from 8-10 years ago. I stayed with regular spinners, one for the boot drive and one to house all the games. The boot drive is a Western Digital Raptor that is 75GB in size, perfect for a boot drive that runs at 10,000 rpm. I then used a 500GB 7200 rpm for the games. That build in the pic I kept for myself, and gave my brother the other build with regular 7200 rpm IDE hard drives.
