Start from scratch

I want to start from scratch so to say, but want to insure that I keep all articles users tags cats and such, after several years of experimenting have a great big mess that has only slowed my site down. To ensure keeping of JUST the main blog, can someone tell me what data base tables to keep, thus being able to start with fresh wp install. I have done something that keeping my blog from showing but all tables in the data base are in tact>

Thanks