You need to list the specs; example-dell model number or motherboard model number, and what hardware you want to change. Your readings are dead on; within +/- 5% is fine. Go to newegg.com and compare your dad's to some good examples from antec, corsair, ocz, seasonic, pc power and cooling, or enermax. None of these brands are cheap, so if you don't have the $$, I would leave the current power supply alone. 90% of desktops use atx ps; micro atx ps are significantly smaller, and you can tell just by looking at them.