You need to copy your original installation files to something like a memory stick, CD or spare hard drive so that you can copy them to a new computer.
While they are on your existing computer you start the executable programs as if you were going to install them.
So in the case of Hoster you find the Hoster507setup.exe file start it and you will come to the page showing 2 choices, upgrade or Remove, choose the remove option and make sure you are on line at the time and follow the rest of the screen instructions, this will automatically inform MTU that it has been removed from that particular computer and allow it to be installed on another computer. Do the same procedure for the other MTU programs.
Depending how old your other programs are they may not auto deregister in which case you would have to inform MTU to move them.
The new computers as you say don't have the old s-video out, most have an HDMI out and some have a VGA out as well. The simplest hook up is the HDMI as most new flat panel monitors now use this type of connection so you just need a standard HDMI lead to connect the two. This type of connection gives excellent picture quality.
Having said that most of us who do actual shows connect to external TV via the ordinary RCA video connection but this requires purchasing an inexpensive converter box from either the VGA or HDMI out of the computer.
Now you may ask why we don't use the HDMI lead as that gives the best picture quality

I can only answer for myself but I have a video mixer that still outputs via standard video so I need to connect through that but another reason is when you go to various bars they all have different set ups and all the older TV have a standard video input and if they don't you can use a scart connector with video RCA video in. Also generally you can find the RCA video inputs on the side or bottom of the TV rather than struggling round the back. Another point is HDMI cables are expensive if you need long runs.
So if your using it at home with a modern TV then go for the HDMI.
But if you need info on the adapter boxes we can advise you on that.