The NEC allows a fix for existing homes that do not have an equipment ground. You can install GFCI receptacles that give some margin of safety and meet the NEC, and some bank loan requirements. Last year I installed over 30 GFCI receptacles in my mother's home that did not have equipment grounding conductors so the she could get a pre-sell inspection approved. As far as the computer, I ran a computer for two years in an older home that did not have a grounding conductor and it worked fine, but I did use all small UPS power unit.
I wrote an article titled How to Ground a Nongrounding-type Receptacle in 1996 based on the 1996 NEC that is at
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Here are the 2005 NEC requirements:
VII. Methods of Equipment Grounding
250.130 Equipment Grounding Conductor Connections. Equipment grounding conductor connections at the source of separately derived systems shall be made in accordance with
250.30(A)(1). Equipment grounding conductor connections at service equipment shall be made as indicated in 250.130(A) or (B). For replacement of non-grounding-type receptacles with grounding-type receptacles and for branch-circuit extensions only in existing installations that do not have an equipment grounding conductor in the branch circuit, connections shall be permitted as indicated in 250.130(C). (A) For Grounded Systems. The connection shall be made by bonding the equipment grounding conductor to the grounded service conductor and the grounding electrode conductor. (B) For Ungrounded Systems. The connection shall be made by bonding the equipment grounding conductor to the grounding electrode conductor. (C) Nongrounding Receptacle Replacement or Branch Circuit Extensions. The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following: (1) Any accessible point on the grounding electrode system as described in 250.50 (2) Any accessible point on the grounding electrode conductor (3) The equipment grounding terminal bar within the enclosure where the branch circuit for the receptacle or branch circuit originates (4) For grounded systems, the grounded service conductor within the service equipment enclosure (5) For ungrounded systems, the grounding terminal bar within the service equipment enclosure FPN: See 406.3(D) for the use of a ground-fault circuitinterrupting type of receptacle.