Let me rephrase this... the current system is only using about 2GB of RAM, just sitting here lol... My concern is that running a Linux distro beside it would max out the RAM... or am I missing the point here.... Only one boots at a time; right, so only one would be using the system resources; is that right?
Yeah, it sounds like that would run Linux perfectly just as it is. (Of course the Alienware had plenty of hardware specs to support Linux as well.) We can figure out if it has Secure Boot or not later, but I doubt it.... and that would be a good thing.
VirtualBox is a nice safe way to test because you never actually install it on your hardware... it runs kind of like an app inside of Windows. So this setup lets both operating systems (Windows + Linux) run at the same time. Also, when you setup the Linux VM, you can control how much RAM is available. The default RAM it wants is fairly low, but with 8 GB you can give more than the default to help support the game requirements... whatever you think it might need. You could actually run 2 or 3 VM's at the same time if you manage the RAM carefully, but there is no need or advantage to that.... its just fun.
So, yes, you are correct that with a "dual-boot" setup... you can only run one operating system at a time. You choose which one at boot time. Linux will set itself up as the default OS, but it can be changed to Windows instead. (Or, in Wizard's case, he can choose from about 30 different Linux distros when he boots up!) Running Linux like this is the same as if it was the only system.... it has full control of the computer and all hardware.
But the "dual-boot" is not as safe to install.... this is a real hardware install and mistakes might harm your Windows partition. It isn't too likely, but this is the place to go slow and pay careful attention... its also a place where you'll learn some new lingo that separates Linux and Windows. This is where we always caution people: BACKUP IMPORTANT STUFF. And even more than that... if you have a name-brand computer (Dell, HP, etc).... it should have a built-in app to create a "System Recovery Set" on DVD or USB (probably DVD's on Win 7, but not sure). The System Recovery Set will let you reinstall Windows from scratch, just like it was the day you bought it. Since you are not ready to get rid of Windows, you should recognize the need to make this Recovery Set before you try to install Linux. If you or your husband built the computer, then you probably also have a Windows 7 Installation DVD.... so that is your safety net if that's the case. But if you have to re-install Windows, you will end up losing everything that was there... other programs you had installed, etc.
If you do a dual-boot install, you can replace that Linux again later if you want to switch... but this will put your Windows at risk each time you do it. But each time you replace it, you learn a little more and the risk is less. You can ultimately remove Linux, but that takes a bit of effort because you have to then restore the Windows bootloader. Linux replaces the bootloader with another one called GRUB because it can boot both OS'es.... the Windows bootloader will not load Linux.
I'd still say to use VirtualBox a bit longer on the Win 7 machine and see if it performs any better for you.... since it is the safer way to go. And you could try out several distros that way without a lot of investment in time or hard drive space. I think the Solus Budgie distro will work in a VM on this computer (and basically prove that Secure Boot is not there).
But you do move along quickly... and when you want to try a dual-boot, then we'll be glad to try to help get you there, and hopefully without any disasters. I have a spare desktop that has Windows 7, and I can go through the steps to install whatever distro you choose before you do, so that maybe I can list off the things to watch for during the install process.
A final comment.... if you have all your backups and Windows Recovery.... the easiest thing is still to erase Windows and go full Linux only!
Then you know you've blown Windows away, but you have to tools to get it back. It takes the stress off of trying to protect Windows and gives you the freedom to install a new distro every day, easily and completely.
Cheers