Tramline,
Welcome to the forum!
I second everything that tarbat says there. The big advantage of RadarBox is that you don't need any 3rd party programmes to get it working. There are "extras" that you can add, like outline files for airspace and extra airport layouts, but you can do these later if you want.
I'm working about 5 miles north of Heathrow in the week, so I'm not too far away if you need any advice. I haven't used Vista, so can't advise too much there, but I've installed RadarBox twice on a Vista laptop without any problems. I'd suggest that you will be able to get any answers you need here on the forum anyway - don't be afraid to ask, even if it's a subject that has been covered before.
The only really critical bit during the install is to make sure you install the RadarBox USB drivers rather than letting Windows do its own thing. It's not a show-stopper if you do this wrong first time, as it's easy to do after the install as long as you know where to look for the drivers. Also, if you plug RadarBox into a different USB port, then you have to install the drives for that port too - this is a know Windows issue, not a RadarBox issue.
All the best
Allocator