Dearsir/madam:ImdelightedthatyouhaveacceptedourinvitationtospeakattheConferencein[city]on[date].Asweagreed,youllbespeakingonthetopic...from[time]to[time].Therewillbeanadditionalminutesforquestions.Wouldyoupleasetellmewhatkindofaudio-visualequipmentyoullneed.Ifyoucouldletmeknowyourspecificrequirementsby[date],Illhaveplentyoftimetomakesurethatthehotelprovidesyouwithwhatyouneed.Thankyouagainforagreeingtospeak.Ilookforwardtohearingfromyou.Sincerelyyours,[name][title]