Towers: MT, Desktop, SFF & USFF Operating System? Windows 7 Pro/ Windows 10 Pro/ Windows 10 Home/ Windows 7 Ultimate and W- XP please contact me for pricing and OS options. . All model computers available as well... i3's/i5's/i7's And Core2 Duo's (HP, Lenovo, Acer and Dell computer Plus Several 2nd generation, 3rd generation and i5 and i7 laptops at very reasonable prices. Fresh install+ fully updated and activated! Units have been thoroughly tested - Guaranteed to be 100% functional. Outer Case may show some minor scratches/scuffs from normal use." Buying Multiple Units? If you are interested in buying multiple pieces you will get discount. Upgrade Memory / Larger Hard Drive / Add Video Cards or LCD or Keyboard/mice? If you need to upgrade the unit - please contact me with your requirements and i will be happy to assist you with the upgrade costs. I can custom build the units to suit your specific needs. These towers come with Pre installed Windows 7 pro/ Windows 10 pro licensed 64 bit operating system ( COA- Activation code is on tower) MS Office Anti Virus VLC Media Player iTunes Adobe Acrobat Reader DC DvD/CD Express Burn power cord (included) Hard drive (500 GB/ 320 GB/250GB/ 1TB, SSds, Ram, Monitors, Keyboards, Mouse, Power cords and HDMI cables are available for a Nominal price?