Really, all you need looking at the Eleven rack is a decent computer to assess what else you might need down the line. The world is full of very cheap desktops with i5 processor and 4 gigs of RAM, which will run Reaper very nicely. Why Reaper? Well, you can try it for free, and that is the full-blown version. It will recognize the Eleven rack right off, as well as all its various outputs. It is logical, intuitive and has great native VST, and will host all the great freeware VSTi instruments, as well as free and licensed VST2 and VST3s without a hassle of any sort. I has a great built in sample player that is very easy to use, and you can really build some convincing drum tracks with just a little searching around the internet for free drum samples, or PM me and I will send you folders full that I no longer use as I now use real drums. It has a convolution reverb, so that you can download, say, the stock presets from the Lexicon 480 (probably the world's greatest digital reverb) for free. They sound amazing, at any price. Download the 32 bit version, as so much of the really great freeware plugins are 32 bit, and of course you want to use Windows, as all those same designers only wrote for PC. Get Windows 7 Professional, it is rock solid and will save you hassles down the road. Look around for a Proteus 2000 sound module from Emu, it will plug right into the S/PDIF input on the Eleven with an RCA cable and for peanuts and a midi cable you will have lots of very usable keys, strings, brass, drums, etc.
I use a 42in Sony TV, I like to see things large, and a really comfortable chair, and hook up to whatever speakers you like to listen to and you are good to go. When you decide you need to record real drums, then you can think about more interface, but with a mic input, an instrument input, two additional line inputs that can become mic ins with either external mic preamps or a board you probably already have, you have all you need to cut quality tracks......