I'm really, really pleased to read your post, Hans.
Even the best companies in the world get things wrong occasionally. The real test of their 'quality' is how good they are at putting things right afterwards. I've always had faith in AC and I'm pleased that it's not been dented through your experiences.
Getting a new computer set up can always be a bit tedious though, so here are a few links which might help you:
1. Although many sites using video streaming are now switching to HTML5, you'll probably need Adobe Flash Player on your computer. (It doesn't come as part of Windows). You can get it from here:
https://get.adobe.com/flashplayer/
(NB: Deselect the 'optional offers'!)
2. Windows also doesn't come with a PDF reader, so you'll need to install one. Adobe Acrobat Reader is the 'standard' (simply because Adobe invented the PDF format) but it's clunky, bloated software. Foxit Reader is the best-known alternative (and well worth considering)
https://www.foxitsoftware.com/products/pdf-reader/
but my own choice is the little-known Sumatra PDF:
https://www.sumatrapdfreader.org/free-pdf-reader.html
3. Windows comes with its own security software but it performs poorly in independent tests. My own choice is Avast:
https://www.avast.com/en-gb/index
4. Windows 7 Pro includes a 'starter edition' of Microsoft Word but, if you need a full office suite, consider OpenOffice:
https://www.openoffice.org/
(If you choose to install it I recommend changing the default 'save' option to use Microsoft formats though. Simple instructions here:
http://helpdeskgeek.com/office-tips/set-openof%EF%AC%81ce-org-to-save-in-microsoft-of%EF%AC%81ce-format-by-default/ )
5. If you need a free DTP program, look no further than Serif PagePlus SE:
http://www.serif.com/desktop-publishing-software/?mc=FSSPAGEPLUS
6. Irfanview is a vastly better image viewer than what comes with Windows:
http://www.irfanview.com/
(If you look 'under the bonnet' though you'll find that it's also got some excellent image-editing features).
Hoping that something there helps you,
Happy computing!
Chris