I used to run mine on a 100W inverter in my car, but then I got a great deal on a Dell travel charger on Ebay. I got a Dell PA-12 travel charger with A/C, car, and plane cables for about $30.

-Jay

I have 3 computers.

One is the CNC controller I put together for the gantry mill I'm building so I won't count that one really. Since it isn't getting used much.

One is my desktop, it has a 160watt power supply running XP-SP3. It has 2GB memory, P4-2.4HT, 128MB AGP Radeon X1050, 200GB 7200rpm HDD, and a 19" CRT monitor (love that thing). I need to get a kill-a-watt but I'm sure the system takes no more than 250w when running full, the monitor is rated to 100 watts max.

My laptop is a Sony, P2-366, 192mb, and the hard drive is a 4gb SSD(Solid State Disk) running Windows 2000(MUCH better power management and plug and play device support, when I had to install drivers in 98 just to use my flash drive I was done with it). I don't have a way to measure this system other than battery usage, it'll last a good 2.5 hours with normal use on wifi and the battery is a 14.4v 4400mAH battery. This comes out to 25.3 watts/hr. I know for a fact that the laptop hadn't been used in years when I got it and I have no idea what the actual charge is that the battery will hold. I imagine it's not 4400 anymore.

I don't actually have numbers on the savings I got from going with a solid state disk from the normal laptop hdd but i can tell you that it's MUCH more responsive now. Not having to wait for a disk to spin up saves a lot of time when coming back from suspend and the 10ns seek time as opposed to 10ms does a lot in an OS like windows that uses many small files. The laptop isn't much for processor or memory but for casual browsing, writing papers, and data logging it works well, not to mention the fact that I can go the full 2.5 hours without the cooling fan ever coming on.

The power bricks supplied with laptops are sized to power the computer, all peripherals and drives (optical mice, USB ports, CD, floppy, hard drive) simultaneously while also charging the laptop's battery in a reasonable period of time. The supplied brick's output capacity usually far exceeds the needs of the computer alone.
That laptop about which I posted had no power block when I bought it ($40 E-bay), but I was able to get a compatible jack installed on a 12v, 1.5amp output wall unit from a cordless phone. It takes nearly 4 hrs to recharge each hour of battery-only use if the laptop is left running, or about a 1:1 ratio with the laptop turned off.

re: Win 98 flash drivers. I found a universal USB driver on line that has yet to NOT be able to run anything. Cameras, memory sticks, traditional drives, hubs... It doesn't support highspeed USB2, nor does Win98 support the U3 technology, but the files (not the programs) are there to import/export.
For any other Luddites that refuse to enter the brave new world of 32 bit OS just to use every USB device, here's the link:
https://www.wintricks.it/faq/usbpen98.html
It's in Italian, but the pictures and images are understandable.

I just remembered, I hooked up an ammeter to the power cable going to some large servers I've got at work...~1 amp at idle.

... at "Watt" voltage?

Standard US AC ~115v.

As a general rule amps x volts = watts. Its not exact, but gives you a real close guestimate.

-Jay

I thought it was the hard-and-fast rule, not a general rule of thumb that gets you close...I thought watts was specifically the expression of amps * volts. What other variables are involved?

I don't remember exactly. My dad explained it to me once, but he lost me fairly quickly. He holds degrees in electrical and nuclear engineering. amps * volts is good enough for most applications, but there was a more detailed way to do it that he did. I remember I asked him once and he started to explain it to me, but when he realized I was getting lost he told me to just multiply the amps by the volts...

-Jay

Yeah, AC power gets technical, with power factors and crap.

I just ordered up a "low power" 45W AMD X2 CPU, with power saving features... but I'm prolly gonna make it suck a few watts more, muhuhahahaaaa.

Though actually it will probably end up a good few watts below what the 125W top of the line screamer does, when I'm getting the same ooomph out of it.