I like the Dat-Omatic that the No-Intro site has, it's really useful, you can download a dat for each system that has all regions, or just US roms if you want, or Jap or whatever. I'm using No-Intro as the main romsets for my PC setup, but there are some games that No-Intro sets are missing, that the RX sets include. First example that comes to mind is the PC-Engine port of 1941 Counter Attack. It's a fully working rom, in the RX sets, but missing from the No-Intro sets. So what I'll be doing is using the No-Intro sets, plus any additional games from the RX sets.