[CentOS] replace x86 with x64 system and reuse existing LVM

I want to replace an existing 32bit with a 64bit installation (Centos 5). 
There's an existing LVM with lots of partitions. Most are used for Xen 
guests. The system itself uses only one of them plus a separate /boot 
partition that is not on LVM.
What's the best course of action here? Should I do the reinstall with 
kickstart or better manually and reuse the existing filesystem? As I 
understand once LVM gets loaded it should find the volumes by itself, but 
will it be able to use the same naming scheme for instance? Or do I have 
to do some additional stuff, anyway?

Thanks,

Kai