Whether it is essential to have 512 mb ram for installing a all-in-one prnt-scan-copy?256 mb ram wont do ?

my coputer (amar pc brand) 3 years old.the dealer said that the all-in-one cannot be installed unless i upgrade it to 512 mb ram.1) if i do this whether it w ill harm my computer? 2) whether any brand of all-in-ones can be installed with 256 mb?