The nice thing in your situation, is that you're not already addicted to payware for this situation. Once they hook you, quitting the habit is nearly impossible for many folks.

So you have a chance to gain control of this aspect of your existence. And hey, if it doesn't work out after a good effort, then you can always visit a street corner and get your fix the old way, for a fee, and then an upgrade fee, and then ...

For your situation, there are a few Linux operating systems ("distributions") that can do the job. Ubuntu is the new kid on the block, but has a massive community support base and tons of momentum behind it. One nit with their "Server" edition, is that it doesn't include a useful GUI by default (WTF?). But that's easily fixed with a single command after installation.

Here is a short article I saw for getting started with Ubuntu Server Edition, including adding on the GUI parts.

Alternatives include Redhat, who have helped the Linux kernel over the years almost as much as they have set back the Linux desktop in the same period with their inferior installation, packaging, and invention of GNOME. But there's a white-label clone available, called CentOS, which is what most people nowadays use rather than "real" Redhat.

Fedora is Redhat's experimental ("unstable") distro, so avoid that for your situation.

Suse Linux is very popular, more so than Redhat, and is probably the best alternative to Ubuntu.

Cheers