Ubuntu Replascement for old XP question regarding processor speed

At the risk of asking a redundant question, (there as just so many, I desire replacing an old XP OS with Ubuntu but really don’t know which version would suit my needs. I desire only a media center type functinality. The older system has a 1.8GHz processor speed when clearly the demo states I require 2. GHz or better. I desire to use my “Magnificent” WIndows 10 desktop for the download. I am networked as best I can to the older system. Help?