Cpanel will eat a lot of VPS memory without any hosted site, have you looked at directadmin? It needs a lot less RAM and it's easy to customize (php/apache versions, mods, etc)
Yea, DA is good with memory, and so is Plesk on Linux. For some reason cPanel just swallows memory like a fat kid eating cake. But, it's still the #1 choice of consumers, so it can't be that bad. As SSPT said, if your going to run cPanel make sure you have more than 256mb of memory.