Restore and clean malware from website. oscommerce

I have a site which is hacked with a huge number of infected files on the server Google lists my site as an attack page also my host has now pulled it due it being full of malware and thus compromising the integrity of their servers it is a oscommerce site - running an old version of osc , Needs to be fixed and secured as its happened more than once now its not a huge site so its not a huge job, only between 100-200 products NO CART just a catalog has ts templates installed will want it moving from osc and copid to another safer alternative maybe joomla ONCE the site is fixed and secured but that willl be another project only respond i u have the required expertise, somebody has already tried but gave up and resorted to backups the site must be cleaned! also contains a gallery using coppermine, it will not allow me to add any new photos so that needs to be fixed. It returns a php error Only proper coders need apply, if you say you can do it i expect it done or will leave appropriate feedback