[CentOS] Possible to install centos keeping folders intact?

Hiya all, just going to do a couple of quick conversions from redhat to centos, an going to back up the folders anyway. But basically just wondering if there's a way to install centos and keep some rather large folders intact without having to backup/restore them. They are based from the root folder, i.e /home but they aren't on a separate partition and want to do a total new install from cd on it. No problem if there is no way, just thought I'd ask to see if anyones ever gone down that route if it is (and yes bad partitioning in the first place! Partly for exactly this reason and others). Thanks in advance, Ian