I have a HP e9120y Desktop , In the last couple of months , These are the upgrades that have been made to computer.
1. Replaced PSU from 300w to 600w.
2. Upgraded video card to geforce gtx 550 ti amp.
3. Upgraded ram from 8 gig to 16 gig.
4. Had to replace the 1tb harddrive , ( Found bad clusters on system files ).
5. Replaced OS with a new retail version of Windows 7 Pro.
At this time not much is left from original computer. ( I.E , Motherboard and Processor , Rom Drives ).
I was thinking about buying new case for more room and upgrading rest of the system. Can I at this point upgrade motherboard and processor and retain OS and Files. I just dont want have to buy another copy of Windows 7.
Also , I was thinking about adding two more hardrives to make a 3 tb Raid 5 Array.