Is it possible to run an x86 binary on an ARM processor?

You may want to switch to an alternative software available natively on your architecture, murmur and mumble come to mind.

murmur and mumble homepage

Short version : if you don't have the source code then no.

Long version : you can use qemu (or kvm or virtualbox, etc) and use a minimal x86 emulated system to run the server.

I guess the answer is "maybe". Usually you can de-compile an executable file, if you know enough about it. If you decompile the code to a language that has an ARM compiler, and the libraries required to compile that binary to your ARM platform, than it should be possible.

For example: If your Ventrilo server can be decompiled into C source code, and this source code is ANSI Standard, you may have enough support with your ARM compiler to recompile the code.

I really don't know if you can do it legally, though, since you would be reverse-engineering a software that you are not the owner.