Will dual screens (large screens) have enough power in a rather old house?

Assuming your computer uses 250 watts which is probably a high estimate, and your monitors use about 100 watts which is probably high for even an old crt, you are using ~450 watts. This means you are probably pulling about 3.75 amps so as long as your circuit breaker is larger than 3.75 amps which I can tell you already it is, then you’ll be okay.

Most likely you have at least a 10 amp breaker possibly a 15 amp. At 10 amps * 120 Volts, your outlet is capable of running 1200 watts, which is well below what your computer needs. At 15 amps your outlet is capable of running 1800 watts. If you want to figure this out for yourself look at your computer and monitor specs to see what the peak wattage is and subtract it from your circuit breaker amperage * 120 volts. Also keep in mind that your peak wattage is not your typical wattage. Your typical wattage is probably about ½ to ⅓ of the peak.

Long answer short you’ll be okay.

You will be fine.

Even older houses had to be built to code back in the day, and unless I’m much mistaken the code on circuit breaker size hasn’t changed much in the last 40 years. Take a look at your electrical panel to see what the capacity of your breakers is. @critter1982 is right – 10 or 15 amps will suit your needs just fine. (side note: most kitchens are wired with 20 amp breakers because of all the heat-generating appliances in most kitchens like ovens and stoves.) All you have to do is make sure you don’t plug too many things into one breaker, and by the sounds of your setup and @critter1982‘s good math skills, you’ll be just fine. If it ends up pulling too much power, the worst that will happen is that you’ll kick the breaker and have to reset it – no big deal cuz that’s what breakers are for!

@camertron: Unless of course it’s a fuse box and not a breaker box, then it could get expensive. :)

I live in a house built in the 1890’s and I run the following from two sockets:

A Computer
Two monitors
An external Hard Drive
A printer/scanner
A wireless router
An amplifier with 4×100w speakers
A tape deck
A MIDI keyboard
A MIDI DJ controller
Two Technics Record Decks
A DJ Mixer
A Television
A DVD Player
and a desk lamp

I will often have them all on (minus the TV and DVD player) at the same time and it’s never been a problem.

I live in a house built in the 1884 (Australia) and I run the following from one socket:
1 x powerboard with soockets to which 2 x power boards with 6 sockets on each, and each socket has its own on/off switch. The mains is connected to one board and the two other boards are connected to the first one. All powerboards are safety switch

I turn off appliances that I’m not using.

2 Computers
one monitor
An amplifier with 6×40w speakers
A tape/clock/radio
A bedside lamp
A Television
DVD Player
VCR player
dvd/vcr
Set top box
2 x Phone Chargers
1 x ipod Charger
1 x laptop
a bed side amp with two speakers
and a desk lamp

But no heater, I’m heat sensitive..

I sometimes have both computers running, the TV and VCR or DVD player. The main problem where I live is that there are 7 other people in the house that also have appliances, including heaters. If someone turns on too many appliances or a power guzzler then the main board safety switch cuts the power.

Make sure your Main Electrical Board has a safety switch otherwise you could have an unwanted electrical fire. If you are unsure about the wiring in an old house, get an electrician to check the wiring.

Like @critter1982 said the monitors are around 100W each, the computer 250W.
Try an experiment. Plug in a dual heat hairdryer and turn it on. Usually those are around 500 W on low and up to 1000 W on high (it will say on the label). If you don’t pop the breaker you’re good.