I really need your help

Dear Friends;
Long Time no hear.
Have not been all that well and had to take a forced Sabbatical.
Forced on me by my Doctor. "Heart".
Anyway, all better now and I am in need of your invaluable advice.
As you know, I Build,rebuild and maintain Computers for various Charities and Benevolent associations.
I would like to be able to check up and repair the units from my own CP at Home.
I sometimes travel 30 miles to get to some of these CPs,"at my own expense"
I have been looking everywhere for over a year, for a program that would be easily installed, easy to run and efficient in it's works.Being on a Pension, doesn't allow me to spend elaborately,if you know what I mean.
I had really wanted to sign in to these CP using nothing more than my XPPro.
However, regardless of the methods or program, I just can't seem to get it going.
There always seems something else that needs to be done and when done I'm just as bad off as I was before.
I could really use you help on this one my friends, surely there MUST be a program or method by which I could access my CPs from my own computer?.
I'd be very grateful for any advice that you could give.
Warmest Regards
My best to all
Aaron