formatting ?

HI,
well i am a beginner. know only little of computers... but still like to keep tinkering with it.
i wanted to install a text to speech freeware on my comp(....especially to deal with huge number of pdf files....) i downloaded few from the sites offering freewares... but since there were not enough details so i tried installing each software. inspite i could not get a ggood program which cud read pdfs without stops. Cud u advise me some nice text to speech freeware (compatible with pdfs)?

secondly since i installed each program and did system restore for each time when they didn't suit purpose....wud that have changed my system files?
do i need to format my laptop ?

 

Thanks Steve for the prompt reply.
wt should i hv done... instead of Sys restore to uninstall .... should i have uninstalled by using add or remove programs. but i heard it still leaves some files/changes behind. wt would have been safer method.