Here's a link that lists the power usage (in Watts) of common computer components; use it as a rough guide to see if your power supply's wattage rating measures up:
http://computer.howstuffworks.com/power-supply3.htm
If you've only got a 250W supply, and your machine is relatively fully stocked with components, I'd get a beefier supply.
Of course, if the power supply is of sufficient
rated wattage but just isn't providing as much "oomph" as it should, that's a different story.
One thing to remember about weak/failing power supplies (or weak batteries, for that matter) is that they will often appear to be putting out the right
voltages if you measure them with a voltmeter, but will not be supplying enough
current, and current is a bit more difficult to accurately measure than voltage.
Before you go out and pay for a new power supply though, replace the IDE ribbon cable on the CDs with another cable that's known to be in good, working condition if you haven't done that already. Also, it is possible that the IDE channel that the CDs are connected to is faulty, which would be a bummer- there's not much you can do there except replace the mobo...