XFX Radeon 5770

yes it is.

Yes, if you motherboard has two PCI-E slots. The HD5770 can handle three monitors btw. If your motherboard has onboard graphics it may be possible to use 4 monitors with just one HD5770 plus the IGP.

Thanks to all. I checked on the possibility of running the 4th monitor off the motherboard, but ASUS said it wouldn't work satisfactorily so I bought a second and ATI is sending me a connecting strap to run as a crossfire unit.

When in crossfire you can only use the 3 monitors off of the first card and you will need an active display adapter to do so. The second card will add processing power to the first for gaming purposes. In order to use four monitors at once you will have to disable crossfire mode in the catalyst control center.

^+1

I don't know what they mean with "wouldn't work satisfactorily" through the onboard, as long as it's a ATi HD3xxx chip or higher that your motherboard has it should work fine in conjunction with any ATi dedicated card.

If your motherboard has a non-ati chip you can buy a cheap basic card like the 5450 just to run the 4th monitor, You'll be doing the gaming off of the 5770's anyway within the first three monitors so it won't affect your performance.

Onboard + 2 5770's should also work fine.

Sorry, it was badly phrased. I'm not a gamer and use the 4 monitors to keep a number of programs open concurrently for research purposes.

As the second card is on the way, I'm sure that I will have enough options to ensure 4 separate monitors.

Thanks again.

You definitely can run 4 monitors off the two HD5770s but those are midrange gaming cards and much more powerful and expensive than you need for your purposes. ANY two current card can handle 4 monitors apart from gaming situations.
If you stick with the HD5770s just remember to leave crossfire off. You don't even need the bridge you mentioned as the only purpose of crossfire mode would be extra processing power for gaming and that will disable the fourth monitor like I said earlier.