I was going to make a post on this, so I hope you don’t mind.
A few months back, I had my computer reformatted and XP re-installed after a previous attempt (which I posted about here) was done incorrectly. The local Best Buy wanted $199 (157 euros) just to look at before deciding what to do. I found a place (a literal hole in the place that’s been in business for over a decade. So they’re doing something right) that did it for $99 (78 euros) with a 7 day guarantee for any problems related to the installation. I don’t know if you’ll run into the same thing in Europe, but you might run into competition charging similar prices despite having the extra overhead of running a brick and mortar place. Also, I was told I was responsible for backing up and restoring any data. The paper authorizing the repair specified that. I assume to protect themselves from lawsuits.