My model railway is a MÄRKLIN H0.
At first time I used Metal-Track. But it was loud and not contact stable. Now I use mainly C-Track. The Locomotivs I bought as used. Some of them are older than 30 years. They are all canged into digital. My digital controller is a TAMS Easy Control. The software is a freeware made by dutch and german guys. It's name is ROCRAIL. It's as good as a profesional software what costs you between 400€ and 600€. They only expect to get a 10€ donation per year. It's for the Internetpages and hardware tests.
The computer. An old 486 ist fast enough. I use a Pentium 1200. The Graphic-Card could have more pixel. And I could need a better monitor.

By the way:

ROCRAIL is usable with all computer-systems - Windows, Linux, and Apple. The leading documentation language is english. You can download it here:

https://launchpad.net/rocrail/+download

and here is the documentation :
http://wiki.rocrail.net/doku.php

In the documentation you'll find a forum. If you have a question, something isn't working. Ask here! An answer could be found sometimes in the same evening.