I have an older house('54). We have two prong outlets.first of all, should I change them over to grounded?....Next. my computer is pluged into a strip w/ a surge prot...the light for "site fault" is on....is this because I needed to use a three prong adapter? Do I need to put the screw through the loop on the adapter?

I'm installing an old ceiling fixture which was just rewired, in a 1927 home with #12 cloth-wrapped wire. The house wiring is all black. I have a tester which shows which wire is hot. The fixture has one wire with a flat side on the insulation, and one that's round. Which fixture wire should be connected to hot? Also, how do you recommend I mark the house wires so I don't have to test each time to find the hot? Any other tips for keeping this old wire safe? What about shrink wrapping an inch or so of the wire? (Colored shrink wrap would also identify the wires). Thanks!