I bought the multimedia Sprint 5787 model with 16 gb of RAM.
The delivery by City Link was a fiasco, but that's got nothing to do with the PC and hopefully it's not typical of City Link.
So far I'm very happy indeed. The computer is fast and very quiet. The inside is very neatly cabled so there's a lot of space. Perhaps that helps them to keep the temperature down and therefore keep the PC quiet.
The PC is also very light for some reason, which I like.
I can't say what the PC would be like running demanding games and the like, but for what I do - watching dvd's, streaming netflix, simple photo editing, word processing and spreadsheets for work and so on, the machine is great.
Don't worry about the lack of an operating system. If you've got a copy of Windows just put the DVD in before you switch on, and if you haven't, download a copy of 'Ubuntu' beforehand, burn it to DVD, put it in before you switch on and follow your nose. I had no problems whatsoever.
For an average middle aged user like me, I would strongly recommend it.