That's what I am fearful of. I have only one computer. If I buy new computer, it will always need to be connected to internet for OS update. Any ideas?
Download and burn a Knoppix or Tails DVD, boot from that DVD, and use the preinstalled Electrum or bitaddress.org or coinb.in from a USB stick without going online.
When you're done, turn off your PC to wipe everything from memory.