My goodness, 23% VAT! I complain about a 9% sales tax in South Carolina. Yes, it's been a very long time. I missed the fact that your current drive is SATA, sorry, but the SATA II should be fine. If I were you, I would reformat when do the clean install of Win 7, just to be on the safe side. But good luck and let us know how it goes.
I am assuming this will be your first dealing with Win 7. I would suggest, after the install, you verify that the Windows Firewall is turned on. You have a lot of Windows updates ahead of you. When you get to A/V security issues, ask. We have a good deal of experience and various opinions of what works best but a general sense of agreement on how to proceed.
Fractal Design R5 | Asus Z170 Pro | Intel i5 6600k | 16 GB G.Skill Ripjaws DDR4 2133 | Seasonic 650w PSU | eVGA GTX 550 TI | Samsung 960 M2 500 GB | Samsung 850 EVO 500 GB | ASUS Burner | Windows 7 64-bit