Most distributions of Linux offer 'compatibility' libraries that enable you to run 32-bit applications on top of 64-bit linux. The names of the libraries differ from distribution to distribution; this article discusses three of the more common ones. Note that these provide the 'bare-bones' compatibility needed, in some cases more libraries may be required. Check online for the FAQs related to your specific distribution.
Some distributions feature kernels with the compatibilty built right in.
64 bit Ubuntu does not install 32 bit support libraries by default. You will need to install two additional packages:
sudo aptitude install ia32-libs
sudo aptitude install ia32-libs-gtk
CentOS / Red Hat
Both of these distributions boast compatibility through the kernel. 32-bit P4V should 'just work' on recent versions of these distributions.
If it doesn't, try the following:
Emerge the package.