No rollback is for something else. Your set is so old now you'd either need to download the full newest romset or run clrmame on your roms and then in utorrent or whatever client you'd have to open the full set torrent and then "select none" then check each one you need (pain in the ass which is why it's easier to stay current). If you stay up to date though then after you are current and a new mame comes out you can just grab the update torrents (labeled something like "161 to 162 update" etc.) and then just drop those into clrmame after a scan and it should be straight. If you want to keep the 122 stuff as is then you'd need to make a copy paste of it all into another folder because romsets change and clrmame is going to edit them into a 161-friendly state which would no longer be a 122-friendly state. I think there is a clrmame tutorial or 2 out there but I don't have links handy.