windows vista is medieval crap OS prob worst released, try laptop or pc that has win 10 on it , connect directly and go into device manager, there might not be drivers available and prob isnt with OS ,but you should see device marked with yellow triangle that would identify that pc is getting some sort of response of unknown device being connected,to start with.
next find out exact model and look for drivers if plotter is old they will be legacy and prob never updated for last 5-10 yrs dunno on the model. if first step successful and you can dig up some drivers revert to windows xp, as vista would even choke good computers nowadays as its complete system and memory drain.
for the person who asked about plotter go with likes of shilouette or the other brand dont remember name atm, its 200-300$ and grand you wont have 30 inch size but its more then enough to do small decals and t shirts and other crap, ive dumped almost 2k into roland gs-24, and let me tell you before you think grand ill do some stickers etc, when you go out there into the market you realize every second joe and dick has one i put up ad i get 2-3 people that will do same or even more, and like you i thought grand ill get one to start with industrial grade but people arent really looking for hobbyists nowadays and market is saturated from all the way to cheap Chinese 1-2$ and free shipping to every other joe doing 20$ deals on anything they can,as many do now printed decals which cost wise is a lot to invest, so if your really just starting drop 500$ that will be more then enough to get small hobby plotter, plenty of vinyls knives mats etc and see how you get on, if it pays off think about investing 2-3k then, as reality is the shops that been in business will have equipment 100x times better then yours and most of the contracts in area, plus hobbysits alike are everywhere, so if you can do some amazing designs that no one else can, and already have customers willing to pay 100$ lined up then think about bigger equipment as otherwise few months later youll realize that you wasted ton of cash and facing competition either someone doing printed vinyl, business cards brochures and so on. I was naive and didnt do research and can tell you straight up look some videos online and people that have skills dont need 30 inch they can easily do it on a4 which will look 10 times better with some craftsmanship and design what they work and create, without breaking a bank and still making some cash on the side, and not even bothering to move up,any time soon. Theres no a,b,c for this business but short term if you can make it with small plotter $ then think moving up, if not its few hundred down the drain not thousand. Now not trying to be a bummer here but research 10 times who does signs in your area look up major stores go on FB and see how many people offer all the same, and ask yourself how you will be different, as i can knock off or redraw any design, come up with my own but im just another person out of at least 20 who can easily do same within 30 miles radius. There is demand but unless you got many connections and someone to help you out, likes of gx-24 isnt worth for starting you can get that any time later if you see demand and need for it. i did nose dive without doing proper research and now honestly i could be easily getting by with small desk plotter, as theres lots to learn, not to mention getting business which is another kind of game, specially once your new, since main profits come from cheap vinyl and selling at markup, many do so but look how long they are in business and how much demand do they actually get to get proper scale and real expectations.
and even if you do have grasp for business side you can always rent one to get a feel, might be a bit expensive but that will put you into market with little strings attached if it doesn't work out, think Roland does that and maybe even graphtec, or 3rd party sellers. As cutting is no brainer part , designs can be outsourced for few bucks nowadays and get done in day or two, and plotters aren't hardware thats hard to come by nowadays as they used to be 10 years ago, its very simillar move that happened with 3d printing just over 6 years they were easily in the thousands and up, nowadays one could be gotten for desk printer price, tech and trends move fast and get cheaper by the day.