All the drivers come on a CD with the computer, so if anything does go wrong, you just insert the CD, and return to the default drivers. All updated drivers are easily downloaded from their respective websites though anyway.
To be honest, if you're the kind of person that struggles with PC's past switching them on, checking your emails and surfing the net, I'd advise against installing an OS on a PC yourself. If however you're reasonably computer literate, it's a piece of the proverbial. This desktop was the first time I'd done it myself, and though I was a bit daunted at first, to be honest it was pretty easy and allowed me a clean, unadulterated (by annoying bloatware and popups!) copy of Windows on my computer.
I read the very same reviews that you did before I ordered the computer myself, and to be honest, they were what delayed my purchase by a couple of weeks whilst I pondered on the difficulties. Seriously, wish I hadn't waited now! It was all that easy… Just remember that if anything goes tits up, revert back to original settings… I think the people that had issues with drivers probably didn't actually insert the driver CD at all… It's included with the PC for a reason, you need to install the drivers before you'll be able to do things such as go on the internet, or have any sound.
If you get one, don't hesitate to give me a shout if you have any issues/worries, I should be able to talk you through anything easily enough.