Re: Dell Optiplex 755, Dell HD 7570 video card, Vista 64-bit
1. install Windows Vista 64-bit
2. install Intel Chipset Software driver
3. install all other drivers
Because Microsoft is no longer providing security updates for Vista, you are opening yourself up to malware if you choose to use the PC online.
If it was me, I would install Linux or CloudReady (which is turns PC into a Chromebook).
Optiplex 755 is certified to run CloudReady.