A week ago i somehow managed to buy fully working HP Proliant DL360 G7 with 2x Xeon X5660 and 48GB RAM for 5 euro, and now i dont know what OS to install, because Windows Server 2012 R2 (which i already installed) dont have enough important drivers to work correctly (like ATI ES1000 driver), about Windows Server 2008 R2 i am unsure, and i havent any experience with Linux server operating systems. What is the best system now for that old server?
If you’re looking to use it to run some VMs and containers - Proxmox. If you’re going to use it as a NAS - TrueNAS.
If the OP is going to use it as a NAS, OP should get rid of it. Westmere is worthless for a 24/7 server. You’ll pay more for power in a year of running it than what a new machine with better performance would cost.