“Price for installing/adding in 4 Mb vs. 8 Mb more memory? My current BestBuy refurbed HP CPU is Windows 7 -- all backed up SW/files need to be windows 7. How much to change from Windows 8.1 to Windows 7, and how much to install the extra memory. Current CPU is in repairs. 8 Mb memory was not enough for Photoshop work, or some other visual programs. Processor needs to be at least 3.0”