Yes, you'll have to reinstall Windows XP if you go down the VirtualBox route, but you won't have to wipe your hard disk first or anything like that.
EPC predates Windows 7 by a considerable margin, and that's probably why it plays silly sods - Win 7 just doesn't do things quite right even in compatibility mode.
VirtualBox is a program you install onto your computer, and it allows you to then install and setup other operating systems without affecting your main one. It basically pretends to be a shiny new PC, and you can have as many of them as you like. It's developed by Oracle now, so a reputable company, and a good bit of software.
You acquire it from
Virtualbox website, choose the link labelled VirtualBox for Windows hosts, then install onto your computer . After that, there's a nice little wizard included which walks you through setting up a new virtual machine, then you can pop Win XP onto it and start and stop it as you wish. Even if you make a complete hash of the Windows XP system it makes no difference because you can just delete the machine and make a new one without any hassle or risk to your Windows 7 system.
Assuming you had a legal copy and product key for the Windows XP that your dead tower used to run, you can get away with using that, or else there are ways and means
