I have this very unit powering my hub and router, and it's fine for that. It will work for smaller computers to help with power blips, which seems to be what we usually receive -- longest outage I've seen was about 30 seconds. On my main system, I have a TrippLite 700VA to power my system listed in the sig.
pugh: You only need to power your monitor, tower, hub, and router (assuming you want to keep your net connection during power failure) -- do you really need the printer, scanner and speakers? Plus, if your printer is a laser, you do NOT want to plug it in for battery backup as it will fry your UPS. You could get away with a 500VA UPS, and if you're on a budget, I'd recommend the PK Electronics Blackout Buster which has four battery backup outlets which can accomodate two "wall wart" transformer plugs that are common with hubs and routers (and 3 surge only, 7 total). They had a $50 rebate available not too long ago on a purchase price of $99. I used that one for awhile, and it worked well enough for me -- my brother is still using it without any trouble.
Otherwise, check out the 500VA BackUps Office model from APC (too late, or I could have sold you one for $90

), or look at some of the ones offered by TrippLite. Some people say good things about Belkin, but I am leery of trusting my equipment to them (anyone know if they are manufactured by someone else?). I would avoid CyberPower -- there is a reason why they are budget priced. Two other good names are Best Power and Patriot, but they tend to be at least as expensive as APC.
One problem I can foresee, however, is that aside from the Blackout Buster, 4 battery backup outlets are difficult to find on one UPS. APC makes some, but they are generally high priced (SmartUPS model has them, for instance). My TrippLite only has three battery and three surge, which is why I ended up buying an additional UPS to supply the hub and router (and to serve as a plug extender/surge).