I think we should talk solutions rather then hosts. You need something custom for sure.
First I would run mysql remotly and make the main server a dual core dual xeon system.
6 gigs of ram is not needed, if anything run 2 gigs of good ram on both servers maybe bump up to 4 gigs if needed.
Without clustering no server will run this.
You looking at about $800 a month for this.
http://www.dwhs.com